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Tire size for 17/18...bit confused
- Thread starter RStom - Hungary
- Start date
So do you attribute any difference in performance, ride, quality of any sort, to the sizes? What I am asking is, obviously the compounds are what make the difference, but now that you've been running two different size setups, what are your impressions on the 215/255 versus the 235/265 based on size alone?
Oh mighty inquisitor......to me the only feel difference on the street between sets is the extra weight of the blitz compared to the other two.Car feels a little more numb and those taller rear do affect the speedo and final drive a little-265/35/18...Now the grip level is very noticible with the ra1 vs the star spec,plus with R compounds on the street you hear a lot more grizzle hitting the fender liner and in fact with windows down on a dirty street in turns I have kicked up pebbles into the cockpit.....btw the rear track set is 275 mm
Dave, to answer your question differently, for tracking with your CTSC you need the 265 or 275 in the rears to put the power down. And if you go with such sizes in the back, you need at least 225-235 in the fronts. It's all about balance.
Not Doc here but just thought I'd chime in.
Sumitomo HTR Z II
I picked up a set of these because they were dirt cheap (relative) and to my amazement work great for the street. They have a nice round shoulder which makes them very predictable and forgiving at the limit. They're actually really fun to toss around. IIRC the set of 4 @ 235/40ZR17 & 285/30ZR18 was well south of $500 installed. They have smaller sizes available too (215/40ZR17 & 265/35ZR18) for even less.
Note: here in NorCal, Discount/American Tire can get these or any tire that Tire Rack sells and will beat theirs or anybody else's price.
I have two sets of identical track wheels @ 17x7.5 & 18x9.5, one mounted with Hoosier R6 @ 225/40ZR17 & 275/30ZR18 and the other with Toyo R888 @ 235/40ZR17 & 285/30ZR18.
At 262rwhp (stockish) this was an optimum setup for technical tracks like Sears Point/Infineon Raceway.
At 406rwhp (currently w/2.3L Wipple) this setup is no longer optimal on my car, especially the fronts. Currently working on solutions to fit 245/40ZR17 & 295/30ZR18.
That is what's on Kips car which is of course my blueprint.
Hrant, I was thinking along the same lines. That the stock sizes are perfect for the engine and trans, brakes, etc. but as you go up in power... I now have a CTSC at around 350 whp and plan on going with Dave Dozier's setup of the twin aerochargers. He is running 400 and 440 depending on tune.
I also now have a stoptech BBK, and of course my made "infamous by my number of questions" KW competition with 1000/600 springs. So the engine, brakes, and suspension are no long stock and beyond what was.
Now I am doing this RSII group buy, and so I was ordering either 17x8 and 18x9 or 18x10 rears. That decision of rear width is a bit dictated by tire choice. To keep TCS ratio identical, with a 215/40, I'd need not a 275 or 265, but a 255 and the perfect wheel for that is the lighter 9" rear.
I haven't been to the track lately, want to do 2 events later. I'm not really at the skill level to need Hoosiers, or probably even R comps, (or probably any of the other shit I've bought lol), but I guess I just need to decide what to do.
Again to keep TCS perfect, if I go 235 front I would need to go 275 rear. What's the thing to do here? So many choices. What would you do? I Have my stock wheels too, but let's keep those out of the equation for now. Let's say I am going t just mount and balance track tires and street tires on the same wheels. Even if I used my stock ones for the track, the fronts aren't really wide enough for a 235. So I think it's really up to the advans to do all the street and track duty, which is fine. I can clean my stock wheels, have the slight curb rash fixed, and put them away in storage.
Dave, I am sure you have heard me say before, there are no perfect answers/solutions to your scenarios since some of them are mutually exclusive.
Your last para makes this clear: as in using the stock wheels for both track and street when you are planning to push 400-440 rwhp. You can't have it both with stock wheels.
My recommendation is for street driving, keep your oem 17/17 with really good street tires BUT being fully cognizant that what you have under the hood is not for play on street tires. Enjoy the initial adrenalin rush from a stop sign/light or getting on a ramp and douse your smile by the time you hit second :tongue:
For track, if you can't haul your tires, I would definitely go with heat cycled (shaved is optional but they last longer if you shave them) RA1 235/275 on 17/18 wheels. The inside liner rubbing is really not an issue since you rarely do a full lock on the track; the only issue you may face is upon compression, the edge of the fender/liner may rub the tires. You can address this with your gazillion KW pro suspension tuning, add a camber kit (push to 3 if you are comfortable - the RA1 likes camber), and you can even slightly stretch the curvature of the fender - a good body shop can do that (you just need the right tool, warm the aluminum and take your time).
Robert, not sure why you need more tires with what you have given the amount of downforce that you are also carrying with that wing. Kip's car had 600+ rwhp and was a totally different animal. I think what you have is ample. Just my $0.02 :wink:
Your last para makes this clear: as in using the stock wheels for both track and street when you are planning to push 400-440 rwhp. You can't have it both with stock wheels.
My recommendation is for street driving, keep your oem 17/17 with really good street tires BUT being fully cognizant that what you have under the hood is not for play on street tires. Enjoy the initial adrenalin rush from a stop sign/light or getting on a ramp and douse your smile by the time you hit second :tongue:
For track, if you can't haul your tires, I would definitely go with heat cycled (shaved is optional but they last longer if you shave them) RA1 235/275 on 17/18 wheels. The inside liner rubbing is really not an issue since you rarely do a full lock on the track; the only issue you may face is upon compression, the edge of the fender/liner may rub the tires. You can address this with your gazillion KW pro suspension tuning, add a camber kit (push to 3 if you are comfortable - the RA1 likes camber), and you can even slightly stretch the curvature of the fender - a good body shop can do that (you just need the right tool, warm the aluminum and take your time).
Robert, not sure why you need more tires with what you have given the amount of downforce that you are also carrying with that wing. Kip's car had 600+ rwhp and was a totally different animal. I think what you have is ample. Just my $0.02 :wink:
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If you're going to use lower-performance tires - and this is not a very good tire (for example, Sumitomo makes a max-performance tire, the HTR Z III, that's much better than the crappy HTR Z II) - then there's absolutely no reason to get the overwide tire sizes. You'd get much much MUCH better performance from narrower tires in a stickier make/model.
I've used both of these tires, the RA-1 and the NT-01. I found their track performance to be very similar to each other. However, I found two advantages to the RA-1. One is, the RA-1 is much better in rain (which is relatively insignificant for most of us, for our track tires). Second is much more important: the RA-1 lasts much longer than the NT-01, for two entirely different reasons. One reason is that the RA-1 comes with deeper tread depth (8/32" vs the 6/32" for the NT-01); the other reason is that the RA-1's profile has a much squarer shoulder so the tire wears out in the middle of the tread, whereas the NT-01 has a rounder shoulder so the shoulder starts showing cords while the middle section of the tread still has significant tread depth.
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The Nitto will be fine too if that is what you prefer - I haven't used them. The heat cycled RA1s tend to last quite a bit, and the fact that you can get them with 8/32 is indeed an advantage if your drives to/from track are long. But 6/32 will give you better grip.
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