Max tire width from front to the rear.

[jaffaz32]

What is the max width a tire can differ from the front to the rear before it messes up the handling?

I know i've asked several questions regarding tires but this is very specific and to the point.

This is not a race car! it is a street car with several track days through out the year.

so if i had a 215 taking the last part from 2"15" (15) how much can it be increased by? for example 50? what's the general rule of thumb?

I appreciate the closer the better but there must be a general rule of thumb a number you can go up to before it makes a big difference ie ruins the handling.

I have established a 215 and 285 is too big that's a difference of 70.

 

[Vega$ NSX]

The two problems with getting a more definitive answer is:

1) The answer is subjective. It's like asking how much pepper is too much pepper to add to a dish? It's a gradient. The further away you get from stock the more imbalanced it's going to feel. However, how far off is completely subjective. For example, I run 305 wide rear tires with 225 fronts. I wouldn't want it any other way, but others would cringe at the idea.

2) There are other factors that come into play when talking about the balance. Weight distribution, alignment settings, suspension settings, tire compound, tire sidewall height, etc. All of this can enhance or mitigate the tire contact patch differential in way or another. All things considered there are too many variables that go into "handling" to put a specific number on the front to rear tire width ratio.

Having said that, the answer is 14.322% :smile:

 

[nsxtasy]

In my experience, the NSX is okay with a "stagger" of 50 mm (such as with 215/40-17 and 265/35-18, a common fitment), but the handling seems to degrade significantly with anything more than that.

The TCS is another consideration when choosing tire sizes; it operates on the difference (ratio) between outer diameters, front vs rear. So it's not the tire width per se, but the outer diameter, which is affected based on the tire width.

 

[bonhamsurf]

I'd like to get as wide as I can on the back, with a good ration to keep the handlin
g as good as possible. I'll have a new engine and turbo kit on it later this month, so I"m considering going to an 17/18 setup. Anyway to get wider than a 285 on the rear without losing TCS and handling? I'd love to get a 295 or 305 in the back.
What setup would you suggest and which tires?

 

[scorp965]

Are you looking for the most well-rounded tire sizes, an aggressive tire size intended to increase contact patch, or simply the challenge of stuffing as much rubber under the fenders as possible?

Standard sizes for 17/18's are 215/40/17 and 265/35/18, significantly larger than the OEM tires, and well-sized for aftermarket wheels.

Aggressive tire sizes, for people looking to increase tire contact batch and handling, while being OK with occasional rubbing, are 235/40/17 and 275/35/18.

If you're in it for the challenge, you're probably going to piss off your TCS system, you're going to have a limited selection of tires, which will be exotic and cost-prohibitive, and you're almost definitely going to experience rubbing issues. I've heard as high as a 245/40/17 in the front, and a 305/30/18 in the rear.

 

[Hapa88]

Here's Bobolinski 18x8 +34 with 215-35-18 and 19x11.25 +48 with 315-25-19

 

[bonhamsurf]

Are you looking for the most well-rounded tire sizes, an aggressive tire size intended to increase contact patch, or simply the challenge of stuffing as much rubber under the fenders as possible?

Standard sizes for 17/18's are 215/40/17 and 265/35/18, significantly larger than the OEM tires, and well-sized for aftermarket wheels.

Aggressive tire sizes, for people looking to increase tire contact batch and handling, while being OK with occasional rubbing, are 235/40/17 and 275/35/18.

If you're in it for the challenge, you're probably going to piss off your TCS system, you're going to have a limited selection of tires, which will be exotic and cost-prohibitive, and you're almost definitely going to experience rubbing issues. I've heard as high as a 245/40/17 in the front, and a 305/30/18 in the rear.

I'm looking for having as much rubber on the ground as I can without pissing off TCS or totally ruining handling. I'll be making 600-700rwhp when I'm done with engine and turbo next month, and my car weighed in at 2745 pounds at a car scale recently. So my goal is to create as much traction as I can to help with the power and light weight. I'm currently running 275/30/19 rears and 215/35/18 up front. I'm willing to go down to a 17/18 setup to increase the rubber on the ground, but not looking to go stupid and decrease the handling. I am adding KW Club Sports plus and Air Lift Suspension, so I have some room to play with my suspension.

 

[DOCMORGY]

Here's Bobolinski 18x8 +34 with 215-35-18 and 19x11.25 +48 with 315-25-19

Now this is just a beautiful NSX you had to go & post (makes me really miss my MCB '97 CTSC) : I am surprised that those 315s fit so nicely in the rear too. Guess alot of it has to do with the offset. Anyways, nice car....

 

[nsxtasy]

Are you looking for the most well-rounded tire sizes, an aggressive tire size intended to increase contact patch, or simply the challenge of stuffing as much rubber under the fenders as possible?

Wider tires don't increase the size of the contact patch; they only change its shape. As long as the tire is inflated reasonably normally, the size of the contact patch depends only on the inflation pressure and weight on the tire. For example, if you have 60 percent of the weight of a 3000-pound car on the rear tires and they're inflated to 36 pounds per square inch, then the size of the two rear contact patches will total 50 square inches - and that will be true regardless of whether you have skinny 205-width rears or 305-width steamrollers.

my goal is to create as much traction as I can to help with the power and light weight. I'm currently running 275/30/19 rears and 215/35/18 up front. I'm willing to go down to a 17/18 setup to increase the rubber on the ground, but not looking to go stupid and decrease the handling.

The primary factor in determining traction is the tire make and model, as reflected in its design features (compound, tread pattern, construction, etc). So if you want to get more traction, concentrate on buying better, stickier tires, rather than wider tires.

Assuming this is for street use (rather than racetrack-only or dragstrip-only use), you can get supersticky "extreme performance" tires in 215/40-17 front and 255/35-18 ('95-05 NSX) or 265/35-18 ('91-93), and they will give you much, MUCH more traction than whatever tires you have now in 215/35-18 and 275/30-19 (since there are no extreme performance tires available in those 18"/19" sizes). Extreme performance tires available in those 17"/18" sizes include the Dunlop Direzza ZII, the Yokohama Advan Neova AD08, and the Falken Azenis RT-615K. If this were my high-horsepower NSX, that's what I would get, for maximum traction.

 

[DDozier]

Wider tires don't increase the size of the contact patch; they only change its shape. As long as the tire is inflated reasonably normally, the size of the contact patch depends only on the inflation pressure and weight on the tire. For example, if you have 60 percent of the weight of a 3000-pound car on the rear tires and they're inflated to 36 pounds per square inch, then the size of the two rear contact patches will total 50 square inches - and that will be true regardless of whether you have skinny 205-width rears or 305-width steamrollers.

I really do not know for sure but I would think this only holds true as long as the load on each tire is static, as soon as the weight is moved from end to end and side to side the size and shape of the contact patch of a given tire will change will it not? For the purpose of dry tire grip, does a wider tire have a wider contact patch? When a tires load/weight is increased the contact patch is limited in width by the width of the tire itself but the contact patch has to grow as the load is increased, it can only grow in length along the length of the tire. Is there a correlation to the loss of grip and the length of the contact patch? If there is then a wider tire would have the potencial for higher grip than a narrower tire, would it not?

Just asking because I do not know, and am in the camp of wider is better for potencial grip.

Dave

 

[nsxtasy]

I really do not know for sure but I would think this only holds true as long as the load on each tire is static, as soon as the weight is moved from end to end and side to side the size and shape of the contact patch of a given tire will change will it not?

Yes, but that is true regardless of the width of the tire. Put more weight on the outside tire in a turn and the size of the contact patch increases, regardless of whether it's a wider tire or a narrower one.

For the purpose of dry tire grip, does a wider tire have a wider contact patch?

Yes, it is wider side to side, but narrower front to rear. This is a slight help in cornering, but is nowhere near as significant as differences in tread compound etc between different makes/models of tires, or even differences in tread depth. The difference is unlikely to be felt in street use. For track use, where hundredths of a second in lap times matter, you may want to go wider.

With the NSX, the simple fact is that there is limited room in the front wheel wells, so that anything wider than a 215 is likely to rub. And going overwide (say, over 265) in the rear without doing so in the front is only going to make the handling worse, and possibly cause problems for the TCS.

Incidentally, at one point the Tire Rack tried measuring the sizes of contact patches on the same car with the same inflation for wider and narrower tires, and the difference in size was less than the 2 percent measurement error in their test.

 

[Vega$ NSX]

I'm looking for having as much rubber on the ground as I can without pissing off TCS or totally ruining handling. I'll be making 600-700rwhp when I'm done with engine and turbo next month, and my car weighed in at 2745 pounds at a car scale recently. So my goal is to create as much traction as I can to help with the power and light weight. I'm currently running 275/30/19 rears and 215/35/18 up front. I'm willing to go down to a 17/18 setup to increase the rubber on the ground, but not looking to go stupid and decrease the handling. I am adding KW Club Sports plus and Air Lift Suspension, so I have some room to play with my suspension.

If you are making 600-700 whp, then there is no sense in running TCS and should be disabled. Every time you get on boost, your tires will slip and your TCS will just slow down the wheels. In all reality, the NSX with as much rubber as you can stuff under the stock fenders can't really apply more than 400 whp or so without slipping. If you keep TCS enabled, then what's the point of going to 600+ whp if you are just going to limit your performance to an effective 400 whp or so with you TCS? Also keep in mind that when you throw 600+ whp to the NSX (especially with a turbo) you are completely changing the dynamics of the NSX already. Wheel size offset and TCS are inconsequential because the car is completely different.

As someone who is pushing between 550-650 whp my recommendation is to push as much, and as sticky a compound, of tire under each fender keeping as close to stock diameters as possible and going no larger than 17/18 wheels. I would also disable TCS and ignore the width ratio between front and rear tires. I would also consider keeping your tires inflated at a lower pressure to try to increase the contact patch within safe limitation. There are multiple reasons for this but the main off of the top of my head is that you will want to minimize tire slip. The first reason is so you'll actually be able to utilize as much of your 600-700 whp as you put a lot of money into. There isn't much point to having that much HP if all it results in a lot of tire squeal and smoke. You could have that at stock HP levels with 125 wide tires. Secondly, with that much power, in 1st, 2nd, and 3rd gear when you get on boost, your back end will very quickly start to slide out (usually to the left) and it is very easy to snap spin your car (thank you mid-engine design.) This can be very dangerous so it will change your driving habits considerably. You'll want to completely lay off boost on corners and only push it when your wheels are straight. As I mentioned before, it changes the dynamic of the NSX to more of a straight line car because it can be very dangerous to get on boost in corners (especially since the turbo is so on/off and not very linear). At that point, you'll want maximum traction and the cornering balance/tire ratio is not as critical.

I set up my car very much to the Factor X racing car (in fact I bought most of their used race car components in my build). But I did that specifically because I found that Factor X did an amazing job in redesigning the NSX to maximize the chassis after adding hundreds of HP. In other words, I think they did the best in maximizing the performance potential of the NSX that now has 400+ more horsepower; and their multiple titles and records seem to confirm that. By following their setup, but balancing it with a more streatable approach, I think it help set up a nice compromise of straight power and cornering performance and safety, even though it violates many typical "stock NSX rules of thumb" that would usually apply.

 

[nsxtasy]

As someone who is pushing between 550-650 whp my recommendation is to push as much, and as sticky a compound, of tire under each fender keeping as close to stock diameters as possible and going no larger than 17/18 wheels. I would also disable TCS and ignore the width ratio between front and rear tires.

Just to note - if you keep as close to stock diameters as possible, you are probably going to have a width ratio that is acceptable to the TCS. Granted, if the TCS is disabled, you're not doing it for that reason, but it will work out that way anyway.

 

[Vega$ NSX]

Just to note - if you keep as close to stock diameters as possible, you are probably going to have a width ratio that is acceptable to the TCS. Granted, if the TCS is disabled, you're not doing it for that reason, but it will work out that way anyway.

Noted, as usual (i.e. much respect for your tire and vehicle dynamics :smile. I'm just saying once you double the horsepower of an NSX, you've turned it into a vehicle in which the TCS was never designed for nor intended. Therefore, I have found it conflicts with intent of the additional horsepower gains and is better off disabled. :smile:

 

[bonhamsurf]

If you are making 600-700 whp, then there is no sense in running TCS and should be disabled. Every time you get on boost, your tires will slip and your TCS will just slow down the wheels. In all reality, the NSX with as much rubber as you can stuff under the stock fenders can't really apply more than 400 whp or so without slipping. If you keep TCS enabled, then what's the point of going to 600+ whp if you are just going to limit your performance to an effective 400 whp or so with you TCS? Also keep in mind that when you throw 600+ whp to the NSX (especially with a turbo) you are completely changing the dynamics of the NSX already. Wheel size offset and TCS are inconsequential because the car is completely different.

As someone who is pushing between 550-650 whp my recommendation is to push as much, and as sticky a compound, of tire under each fender keeping as close to stock diameters as possible and going no larger than 17/18 wheels. I would also disable TCS and ignore the width ratio between front and rear tires. I would also consider keeping your tires inflated at a lower pressure to try to increase the contact patch within safe limitation. There are multiple reasons for this but the main off of the top of my head is that you will want to minimize tire slip. The first reason is so you'll actually be able to utilize as much of your 600-700 whp as you put a lot of money into. There isn't much point to having that much HP if all it results in a lot of tire squeal and smoke. You could have that at stock HP levels with 125 wide tires. Secondly, with that much power, in 1st, 2nd, and 3rd gear when you get on boost, your back end will very quickly start to slide out (usually to the left) and it is very easy to snap spin your car (thank you mid-engine design.) This can be very dangerous so it will change your driving habits considerably. You'll want to completely lay off boost on corners and only push it when your wheels are straight. As I mentioned before, it changes the dynamic of the NSX to more of a straight line car because it can be very dangerous to get on boost in corners (especially since the turbo is so on/off and not very linear). At that point, you'll want maximum traction and the cornering balance/tire ratio is not as critical.

I set up my car very much to the Factor X racing car (in fact I bought most of their used race car components in my build). But I did that specifically because I found that Factor X did an amazing job in redesigning the NSX to maximize the chassis after adding hundreds of HP. In other words, I think they did the best in maximizing the performance potential of the NSX that now has 400+ more horsepower; and their multiple titles and records seem to confirm that. By following their setup, but balancing it with a more streatable approach, I think it help set up a nice compromise of straight power and cornering performance and safety, even though it violates many typical "stock NSX rules of thumb" that would usually apply.

Great suggestions. The car is my daily driver, so a blend of sticky and reliability is best. I'm currently running the Yoko S-Drives on the car and have been enjoying them much more than I thought I would. Until I recoup the costs of the engine, I'll be stuck with my 18/19 wheels for awhile.

Wheels/offsets/etc are the one part of a car I'm pretty ignorant on, so it's a constant learning process for me.,

 

[Vega$ NSX]

Great suggestions. The car is my daily driver, so a blend of sticky and reliability is best. I'm currently running the Yoko S-Drives on the car and have been enjoying them much more than I thought I would. Until I recoup the costs of the engine, I'll be stuck with my 18/19 wheels for awhile.

Wheels/offsets/etc are the one part of a car I'm pretty ignorant on, so it's a constant learning process for me.,

Remember that the stickier the tire, the less tread life it's typically going to have. So, as you say, being a daily driver you'll definitely want to balance a between sticky and longer life tire. There are lots of good options out there that I'm sure the guys here can recommend that are good balance between the two. But something to consider. If you go with a less sticker tire to save on the tread wear life at much higher HPs you are only going to get more and more tire slip (burnouts). What that means is that you won't be able to take advantage of all that additional HP you will be putting into your engine. For example, if you can break your tires loose at 420 whp, then you won't be any faster if you add another 200 whp (620 whp) because you'll just keep spinning your tires. If anything, you'll be faster at 420 whp because you will spool up quicker and with less HP, give your tires a chance to actually catch up with some traction. At 620 whp, you can pretty much assume every time you get on boost full throttle you'll just be spinning tires the whole time (or some TCS will just limit your power). And I can tell you to go from 420 whp to 620 whp isn't linearly more expensive. It's exponentially more expensive. You can get away with a stock motor at 420 whp. But I would definitely not recommend it at 620 whp. Also, you'll find weaknesses in the transmission, axles and other parts past the 600 whp mark that will be expensive. The second thing to remember is if you go with a less sticky tire to save tread wear life, depending on how much power you have and how you drive, you could actually end up with less tread wear life simply because you'd be doing burnouts all the time. Now if you lay off boost, then you'll be fine, but if you can't say no to straight open roads from a stop or you like highway merge onramp lanes and get on boost a lot, you'll be burning through tires really quickly. But then again, in Hawaii, with so much traffic, it's pretty hard to be able to open up a lot.

Since you'll be keeping your 18/19's for a while (like I did after I boosted) then I would recommend staying in the 400-450 whp range. Not only will it be plenty of power, but it will pretty much be as much as your tires can handle, and it will save you a ton of money on your build. When I got up to about 460 whp, I was running 18/19's (225 wide front, 275 wide rear, Bridgestone Potenza S03's an all round performing tire). After I started jumping into the 500-650 whp that tire setup was worthless. It was like driving on ice and I had absolutely no confidence in the car. I bought the Factor X Gen 1 racecar wheels/tires: 17/18 (235 wide front, 305 wide rear, Toyo RA-1/R888 R compound tires) and I feel like I have one of the more stable high HP cars around. I give my keys to people all the time and they constantly remark how easy it is to drive around with that much HP. Many of my friends who have never driven anything more than 200 HP have had no problems opening it up. Although I did have to go widebody in order to fit all that rubber underneath the body panels. It did throw off my TCS (so it's permanently disabled) and it did change the dynamics of the car quite a bit. But I had Billy Johnson (Roush and Factor X driver) completely change my alignment and suspension specs to compensate and the changes he made were amazing. Put it right back into a great balance. So much so, I can get into full boost, and take my hands off the steering wheel and ride it up to redline. So basically, there are tweaks you can do to compensate if you have a bad front/read tire size ratio imbalance, though it helps to have an NSX race team to call on. :smile:

By the way I had a great time on Oahu the first two weeks of this year. Finally ran up Koko Head Trail this time instead of just looking at it and it was awesome! Great view!

 

[bonhamsurf]

Remember that the stickier the tire, the less tread life it's typically going to have. So, as you say, being a daily driver you'll definitely want to balance a between sticky and longer life tire. There are lots of good options out there that I'm sure the guys here can recommend that are good balance between the two. But something to consider. If you go with a less sticker tire to save on the tread wear life at much higher HPs you are only going to get more and more tire slip (burnouts). What that means is that you won't be able to take advantage of all that additional HP you will be putting into your engine. For example, if you can break your tires loose at 420 whp, then you won't be any faster if you add another 200 whp (620 whp) because you'll just keep spinning your tires. If anything, you'll be faster at 420 whp because you will spool up quicker and with less HP, give your tires a chance to actually catch up with some traction. At 620 whp, you can pretty much assume every time you get on boost full throttle you'll just be spinning tires the whole time (or some TCS will just limit your power). And I can tell you to go from 420 whp to 620 whp isn't linearly more expensive. It's exponentially more expensive. You can get away with a stock motor at 420 whp. But I would definitely not recommend it at 620 whp. Also, you'll find weaknesses in the transmission, axles and other parts past the 600 whp mark that will be expensive. The second thing to remember is if you go with a less sticky tire to save tread wear life, depending on how much power you have and how you drive, you could actually end up with less tread wear life simply because you'd be doing burnouts all the time. Now if you lay off boost, then you'll be fine, but if you can't say no to straight open roads from a stop or you like highway merge onramp lanes and get on boost a lot, you'll be burning through tires really quickly. But then again, in Hawaii, with so much traffic, it's pretty hard to be able to open up a lot.

Since you'll be keeping your 18/19's for a while (like I did after I boosted) then I would recommend staying in the 400-450 whp range. Not only will it be plenty of power, but it will pretty much be as much as your tires can handle, and it will save you a ton of money on your build. When I got up to about 460 whp, I was running 18/19's (225 wide front, 275 wide rear, Bridgestone Potenza S03's an all round performing tire). After I started jumping into the 500-650 whp that tire setup was worthless. It was like driving on ice and I had absolutely no confidence in the car. I bought the Factor X Gen 1 racecar wheels/tires: 17/18 (235 wide front, 305 wide rear, Toyo RA-1/R888 R compound tires) and I feel like I have one of the more stable high HP cars around. I give my keys to people all the time and they constantly remark how easy it is to drive around with that much HP. Many of my friends who have never driven anything more than 200 HP have had no problems opening it up. Although I did have to go widebody in order to fit all that rubber underneath the body panels. It did throw off my TCS (so it's permanently disabled) and it did change the dynamics of the car quite a bit. But I had Billy Johnson (Roush and Factor X drive) completely change my alignment and suspension specs to compensate and the changes he made were amazing. Put it right back into a great balance. So much so, I can get into full boost, and take my hands off the steering wheel and ride it up to redline. So basically, there are tweaks you can do to compensate if you have a bad front/read tire size ratio imbalance, though it helps to have an NSX race team to call on. :smile:

By the way I had a great time on Oahu the first two weeks of this year. Finally ran up Koko Head Trail this time instead of just looking at it and it was awesome! Great view!

Again, great info and I appreciate it. I won't be running a stock engine. I bought the engine out of Cody's Pike Peak Race car. He's doing a full rebuild on it, so it's the "LF1200" , capable of handling 1200hp, but of course I'm not going for that. I'm also buying the 1-off Exedy clutch from the pike's peak car, so transmission will be ready. Add my 4.23 NSX-R Final Drive Differential that I already have in the car so should be pretty fun

 

[Vega$ NSX]

Again, great info and I appreciate it. I won't be running a stock engine. I bought the engine out of Cody's Pike Peak Race car. He's doing a full rebuild on it, so it's the "LF1200" , capable of handling 1200hp, but of course I'm not going for that. I'm also buying the 1-off Exedy clutch from the pike's peak car, so transmission will be ready. Add my 4.23 NSX-R Final Drive Differential that I already have in the car so should be pretty fun

Very nice build! You are definitely approaching it the way I 100% support. Build/use a bullet proof engine and only boost to a fraction of it's potential. If you stay with a conservative tire setup, you'll keep the torque stresses down on the other components, which is good. You'll have a high HP NSX that you can beat on all day long for as long as you want. The only thing I can offer is you may want to try out that Exedy clutch for a while first. It's a great clutch, especially for the HP, but for a daily driver, it can get a bit tiresome.

 

[TURBO2GO]

Doesn't the tires's "desire"... for the lack of a better word... To stay round, at some point limit the vertical contact patch (I'm going to call it vertical and horizontal looking at it from above). And if that gets limited, and you are at max horizontal because of width, then you have effectively decreased your contact patch.

I understand the whole weight pressure thing, but I think as Dave pointed out it is easy when static and gets complicated really quick with motion. I mean if we take it to an extreme... Lets say go from a 265 to a 155 section width tire... Inflated to the same pressure... And on the same car at the same weight... I highly doubt that contact patch will still remain the same. I think that math only applies within certain parameters.

And then there is the whole thing of DRIVE. The stress and shape of the tire changes when it is on the front non-drive wheels to the rear drive wheels where it is dealing with force in two different directions on acceleration and in a turn.

I think the saying "contact patch remains the same and is only dependent on pressure and weight" is actually a lot more complex than it sounds.

 

[nsxtasy]

The principle remains valid (and, as noted above, has been tested and proven) when all variables are within relatively normal ranges. It remains true on a static basis as well as a dynamic basis; the only difference is that the weight on the tire varies dynamically (and, to a lesser extent, the pressure can change with the tire temperature). And don't worry about extremes, those BS fantasy questions people ask like "what if the tire pressure is 2 psi", "what if the tires are 75 mm wide", etc.

 

[bonhamsurf]

Very nice build! You are definitely approaching it the way I 100% support. Build/use a bullet proof engine and only boost to a fraction of it's potential. If you stay with a conservative tire setup, you'll keep the torque stresses down on the other components, which is good. You'll have a high HP NSX that you can beat on all day long for as long as you want. The only thing I can offer is you may want to try out that Exedy clutch for a while first. It's a great clutch, especially for the HP, but for a daily driver, it can get a bit tiresome.

You're spot on. I want a bulletproof engine, which is why I'm swapping it out. My current engine only has 87,000 miles on it and it runs like a champion, so I'll be selling it when I do the swap.

The clutch is actually a one-off that was designed to be closer to daily driver due to the uphill and curve factor of Pikes Peak race. I'd rather feel secure that there's something in there that can handle the extra power. It can't be any more tiresome than what's in my 1969 bronco. Besides, I do kokohead 2 times a week, sometimes more, so I should be ok.

Speaking of which, "By the way I had a great time on Oahu the first two weeks of this year. Finally ran up Koko Head Trail this time instead of just looking at it and it was awesome! Great view! " It's one of my favorite workouts to do every week. You should come back for a visit.

 

[bonhamsurf]

So as much as I'd like to go to a 17/18 setup, I'll never get a 17" around my front calipers and I'm not going to replace them.
Sooo... Here a question in sure will get me flamed for asking, can I run 18" on all 4 tires?

 

[nsxtasy]

Here a question in sure will get me flamed for asking, can I run 18" on all 4 tires?

You can, but most folks with 18" front wheels go with 19" rear wheels. The tire sizes you'll want are:

18"/18": 215/35-18 front and 265/35-18 rear
18"/19": 215/35-18 front and 275/30-19 rear ('91-93 NSX)
18"/19": 215/35-18 front and 265/30-19 rear ('95-05 NSX)

None of the "extreme performance" tires are available in 215/35-18 though, so you'll take a hit in performance. The best tire available in these sizes is the Sumitomo HTR Z III.

 

[bonhamsurf]

You can, but most folks with 18" front wheels go with 19" rear wheels. The tire sizes you'll want are:

18"/18": 215/35-18 front and 265/35-18 rear
18"/19": 215/35-18 front and 275/30-19 rear ('91-93 NSX)
18"/19": 215/35-18 front and 265/30-19 rear ('95-05 NSX)

None of the "extreme performance" tires are available in 215/35-18 though, so you'll take a hit in performance. The best tire available in these sizes is the Sumitomo HTR Z III.

Thank you for the info. As expected, now that the new engine is in and the turbo is in, my 275's are pointless in the back, and this is under most normal circumstances, as I haven't even pushed the car off the line and I'm not even going into boost. Between Cody's Pikes Peak engine and the twin disk Exedy racing clutch (which doesn't engage until 50% of the way out, and yes, they confirmed this is the way that clutch is) the rears spin often. Living in Hawaii means some extreme hills while starting off at a stop light.

Anyways, I have less than 2cm of clearance between my front brakes and my current 18's, they are the first generation Project MU's, so I can't put 17's on the front. Trying 18's all around is my only option, but only if I can get 295's or 305's on the rears.

With that being said, using the numbers "18" in a search on the forums doesn't work as it's too few of characters. I've been reading for several days trying to find anyone else's experience in this. Any input or links to forums? Thanks!

 

[bonhamsurf]

Very nice build! You are definitely approaching it the way I 100% support. Build/use a bullet proof engine and only boost to a fraction of it's potential. If you stay with a conservative tire setup, you'll keep the torque stresses down on the other components, which is good. You'll have a high HP NSX that you can beat on all day long for as long as you want. The only thing I can offer is you may want to try out that Exedy clutch for a while first. It's a great clutch, especially for the HP, but for a daily driver, it can get a bit tiresome.

So after weeks and weeks of searching, the only rims in 17/18 that I really love are the Wedssports SA60M.
The only sizes I could do would be

17x7.5+48
18x10+36

I know I'd have to run a 15mm or 20mm spacer up front. Other than that, do you foresee any other issues. If I did these rims, I could run the new ADVAN Neova AD08 R tires I love in
Fronts - 215/40/70
Rears - 285/30/18 or 295/30/18