Suspension question... again...

[NSX UNITED]

I've read many posts about people with different suspension setups with the 18/19 combo. It seems like the majority with aftermarket rims tend to lower the car quite a bit. In the future, I will be using coil overs so adjusting ride height isn't a problem.

My questions are:

1) How much do I have to lower the car in order to have the exact same height as the stock rims/suspension with the 18/19 combo? Again, it *seems* like most people with 18/19 combos tend to lower the car lower than stock height. I just want the ride height to be the same except with bigger rims. Are there any measurements available or do I need to adjust the coil overs through trial and error? Also, will the tires rub at all?

2) I've read somewhere that Tein RA will take 12lbs off the unsprung weight. Does it mean getting rims that are 12lbs heavier than stock will result in same performance as the bone stock combo?

Please enlighten me here, I've these questions in my head for a while now. Thanx in advance.

 

[jbum]

i'll take a stab at this but correct me if i'm wrong guys..

1. as far as ride height, bigger rims shouldn't mean bigger diameter wheels. it's all about the tires you use. if you get the right size tires, you should be able to get the same diameter, hence the same ride height as stock.

2. i guess if you want to be technical, heavier wheels will cause the engine to use more force to spin the wheels compared to lighter wheels. but the car is now ligher above the wheels... i'm just babbling now. but at 12 lbs. i don't see a whole lot of difference between stock and this setup.

 

[D'Ecosse]

Well, jbum is partially correct - that applies OK up to 17/18 combos, where you can match the outside diameter of the tire by changing the aspect ratio - see the Tire FAQ for how this transpires into real sizes.
The problem with 18/19 combo is that you cant really get a small enough aspect ratio to make the size the same.
(I run 18/19 myself.)
So, using the Tire diameter formula at Tirerack, we can calculate the sizes of the 18/19's
The fronts, 225/35/18 give a rolling diameter of
457.2 mm (=18") + (225*0.35)*2 = 614.7mm = 24.2"
The rears, 275/30/19 give
482.6mm (=19") + (275*0.3)*2 = 647.6mm = 25.5"
(Use Metric conversion for in/mm/in conversions)
Now stock front / rear is 23.1" (23.6") / 24.7" (24.9") for 91-93 & (94-01), so is between 0.6" - 1.1" larger diameter at the front & 0.6" - 0.8" larger at the rear.
Taking the worse case for the increase from 91-93, this would be 1.1" at front & 0.8" at rear, but ride height would only be affected by 1/2 of that, or 0.55" & 0.4".
So, the short answer is that if you lowered your car by approx 1/2" front & rear, the chassis ride height would be the same as stock. However visually it would appear to look much lower, due to the larger wheels filling the now lower well with respect to them.
Hope that helps - sorry if it is long-winded.

 

[nsxtasy]

The problem with 18/19 combo is that you cant really get a small enough aspect ratio to make the size the same.

You can, but your tire choices are extremely limited. That's just one of numerous problems with the 18"/19" combo, as noted here.

There are lots of tires available in 17" front and 18" rear sizes for the NSX, so those wheel sizes make a lot more sense. Plus, you won't have to worry as much about those other problems, like susceptibility to damage from potholes, etc.

 

[NSX UNITED]

Thanx guys for the replies.

Ken,

I'm sorry to bring this up as I see you might be getting quite aggrivated that people aren't aware of disadvantages of bigger wheel sizes. One of the reasons I'm still running stock is because I've read many of your posts I've been and still am being torned between looks and performance. However, I'm still really tempted to go 18/19 despite the inconviniences. As for tire sizes, I tend to go with 225/35/18 and 275/30/19 just like D'Ecosse and the others (ironically, my eye sights are also -225 and -275, I think it's a sign). Tires are very limited but there are always Potenza S-03s.

D'Ecosse,

Thanx for the accurate numbers. It took me sometime to absorb the information because I really didn't have a clue about suspensions. I've got a few questions, hope you don't mind answering them.

1) How much did you lower your car with the 18/19?

2) What spring rate are you running?

3) Is the car noticably slower with the bigger wheels?

4) How heavy are your wheels?

That should be all

 

[Zishan]

Well, I went from stock 15/16's to the 18/19's. I have to say that I honestly feel a *slight* decrease in performance. I'm running 18x8 and 19x10's with 225/35/18 & 275/30/19's. But the looks out way the slight performance decrease. Wheels totally change the look of a car. The NSX now looks very wide and exotic'er! In my opinion, the wheels were worth every penny!
Also, I've put the wheels(18/19's next to the stock(15/16's) and they seemed to be almost the same height. When mounted on the car thou, my car is definitely higher!
My car's lowered almost 2 inches also. And the wheels seem to be very light for 18/19's.
Regards
Z

 

[nsxtasy]

I'm sorry to bring this up as I see you might be getting quite aggrivated that people aren't aware of disadvantages of bigger wheel sizes. One of the reasons I'm still running stock is because I've read many of your posts I've been and still am being torned between looks and performance. However, I'm still really tempted to go 18/19 despite the inconviniences. As for tire sizes, I tend to go with 225/35/18 and 275/30/19 just like D'Ecosse and the others (ironically, my eye sights are also -225 and -275, I think it's a sign). Tires are very limited but there are always Potenza S-03s.

Don't be sorry; I'm simply trying to make sure you (and everyone) have all the information you need to make an informed decision. If you see all the pluses and minuses and decide to go with bigger wheels anyway, that's fine! For that matter, I've mentioned repeatedly how lots of folks are having excellent results ("looks and performance", as you put it) with 17" front and 18" rear wheels - not stock, but not quite as severe as the 18"/19" combination.

If I had to go 18"/19", I wouldn't want front tires that rubbed the fender well liners, so I would probably get something like a Kumho MX in 215/35-18 in the front, and 245/35-19 in the rear. That would help handling by using the same treadwidths and "stagger" as the stock '94-01, the TCS would be okay, and it wouldn't hurt performance (or increase ride height) as much as the even larger tire sizes mentioned above do.

 

[NSX UNITED]

17/18 combo isn't enough of an incentive for me to go aftermarket. Since I want to have bigger wheels, I might as well go all out to 18/19. I have this fear if I went with 17/18, one day I'd regret why didn't I buy bigger ones. This is the max that I'll go, 19/20 will never cross my mind.

Is there anyway for 225 fronts not to rub at all? Providing I will only lower the car to stock height. I don't need spacers, do I?

 

[X-TNSIV]

1) How much did you lower your car with the 18/19?

2) What spring rate are you running?

3) Is the car noticably slower with the bigger wheels?

4) How heavy are your wheels?

That should be all

FYI running HRE 547's with 225/275 tires...

1) I will measure the center hub to the fender tonight for you.

2) I'm running the tein RE suspension, please refer to SOS for spring rates

3) the car is MUCH slower than with the stock wheels for acceleration & braking

4) Front wheels/tires are ~44lbs each
Rear wheels/tires are ~55lbs each

 

[NSX UNITED]

Thanks for going through all the trouble in telling me your specs. I really appreciate it.

As I know that you're a heavy modder, how off is my assumption if I were to assume an NSX with modded I/H/E + 18/19 would accelerate somewhat close to a stock NSX with 16/17?

Now that you've mentioned your car is much slower with 18/19, why do you still have them on? Reason for asking is that your mods to the X are straight out performance, makes me wonder why you won't drop to 17/18. For me, it's all looks

 

[X-TNSIV]

Thanks for going through all the trouble in telling me your specs. I really appreciate it.

As I know that you're a heavy modder, how off is my assumption if I were to assume an NSX with modded I/H/E + 18/19 would accelerate somewhat close to a stock NSX with 16/17?

Now that you've mentioned your car is much slower with 18/19, why do you still have them on? Reason for asking is that your mods to the X are straight out performance, makes me wonder why you won't drop to 17/18. For me, it's all looks

I gained something like ~12lbs over stock per front wheel and ~15lbs over stock for each rear.

I would not assume that the larger wheels would rob that much power from the car, but when I feel it most is roll on power on the freeway. the sprung weight makes a considerable difference.

in regards to the question on why I chose the 18"/19" set-up...I originally had a set of 18"/18" Volk LE37T's (same as TE37's), yet they were still in the range of about ~38lbs each front and ~50 lbs rear. the tires contribute a majority of the weight (pretty close to the weight of the wheel, if not more in some cases). These wheels were great, but would not accomodate a big brake kit, so I ended up selling them for a set of HRE's instead. Plus I like the larger wheel look. I think of it this way...regardless of what I do to my car to make it quicker, there will ALWAYS be someone faster...

Measurements are taken from the center of the wheel to the actual metal of the fender well:
13.5" in the front
14.25" in the rear

Allen

 

[ScienceofSpeed]

As mentioned, if proper sized tires are used, ride height or suspension clearance shouldn't be a problem (see note below). However, more important is wheel/tire width and wheel offset. You can use this handy calculator to determine distance from the suspension and the inner wheel edge here:

http://toy4two.home.mindspring.com/offset.html

Cheers,
-- Chris

 

[D'Ecosse]

D'Ecosse,

Thanx for the accurate numbers. It took me sometime to absorb the information because I really didn't have a clue about suspensions. I've got a few questions, hope you don't mind answering them.

1) How much did you lower your car with the 18/19?

2) What spring rate are you running?

3) Is the car noticably slower with the bigger wheels?

4) How heavy are your wheels?

That should be all

Sorry for the delyed response - been in China & had only dial-up access!

1) None yet, I would like to drop it about an inch, probably no more than that - too many problems with driveway otherwise.

2) Stock

3) No - I can honestly say it is not perceivable. I am really surprised by X-TNSIV's comment that he feels its is "MUCH slower" - I wouldn't think the perception would be at all noticeable in the real world & I doubt if even 1/4 times are radically affected (although theoretically there will be advantage with lighter wheels)

4) Sorry, not sure - I'm not hung enough the weight thing to care, personally.

My car was parked next to another NSX at the weekend & although both had stock suspension, mine "looked" noticably lower (although from my earlier calculations it should in fact be higher - however the visual impression of the wheels in the well is what makes the difference)

This is how they look .......