ForcedFedRS

iTrader: (23)

I didn't make my post very clear. There would be no difference in contact patch if you were running the same witdth tire/rim 17 and 18. My 17's are the factory wheels w/255's, the 18's are 18x9.5's w/275's. What I was implying was if your going to run a tire that is super wide, it is hard to do that with 17's. Some run a 275/40/17, but the sidewall is fairly tall, and if you planned on going with a wider tire, you may not have much luck finding the size for you. So for wider tire usage, an 18" wheel allows for a smaller sidewall, and the same width. Also, the selection of wide 18" tires available is huge. You can also go extremely wide with an 18" wheel, some evo guys are running 305's. I don't think there is anyone on a 17" wheel doing that. Hope this helps. Sorry for my vague post earlier.

cij911

iTrader: (14)

Jason -- Thanks for the response and clarification. For my needs (street and maybe a weekend event once in a while) I think I'll just try to find a nice light set of 17x9 or 17x9.5.

theshadow

I've tried 17x8.5 FN01RCs with 235/45/17s and 245/45/17 Bridgestone RE55s and Toyo R888s on them and the 245s generated more lateral Gs and quicker lap times on my Performance Box than 18x9.5 Rota P45Rs with 285/30/18 Pirelli Corsas ever could. And I tried hard to do the 285s justice!

Goes to show that tire selection (brand, compund, pressure) is just as, if not more, important than just sheer size.

I also found that the clearance issues with +30 P45Rs and 285/30/18s were simply too annoying in the end, plus I could really feel the extra unsprung weight in the transitional handling behaviour of the car. BUgged me so when I finally banged up the 18x9.5s I just gave up and went smaller.

I think the perfect compromise (for teh road course at least) is going to be 265/35/18 R888s on my 18x9.0 Rota SVNs. Plenty wide, plenty good tires but not too wide.

jid2

iTrader: (62)

I just picked up some 18x9.5 NT03's and am mounting 265/35/18 BFG R1's on them. I think that should be niiiice.

ForcedFedRS

iTrader: (23)

Some setups just simply do not have the power to justify something like a 285. A fast track car that does have the power can justify something like a 285.

ForcedFedRS

iTrader: (23)

If it is mainly a street car and mild track events, I would definately stick with something in the 17" size. Good luck!

dsmbruno

iTrader: (21)

Aren't Rota wheels a little on the heavy side? Maybe that will affect the performance and even "rob" u power. I think the 18' P45r's are around 22lbs and lets say the NT03's are around 18lbs. Thats roughly 4lbs of extra wheight in each corner... just throwing that in to help me make a decision as I might want to get into road racing...

boomn29

iTrader: (47)

Rota's are heavy and not the best quality either (don't ask me how I know).
Just keep in mind the cornering forces you're asking your rims to withstand on the track. A LOT of people run Enkei and Volk on the track as they are strong and some of the lightest out there. 5Zigen are a cheap alternative that a lot of people run too.

nils

iTrader: (56)

for the money its hard to beat the enkei nto3m's....

theshadow

Yeah if I had the money I'd get lighter rims for sure...I seem to go through rims like underwear though. Rotas I can afford at least. :P

Oh and yes, 18x9.5 Rota P45s are heavy as heck. My 18x9.0 SVNs, not so much.

Another factor to consider is that for maximum grip you need to be working the rubber hard enough to keep the tires wearing at the optimal rate (odd as that may sound). Too cold and you're just wasting traction - too hot and you glaze the tires over.

It's basically a matter of heating them up to a temp where the rubber molecules are able to break their bonds without melting together to much (i.e. glazing). The worn outer rubber layer continually wears off, exposing the next fresh layer and soon and so forth.

I suspect that depending as tires get lwider and/or compounds harder you'd need to work the tires harder and longer to get them up to optimal temp since you have more surface area to deal with.

The right alignment and pressure would also need to be dialled in yso that you're abe toget uniform temps across the tire in order to maximize the use of your contact patch.

I'fmguessing all of this this might be partially why I was quicker on 245s than on 285s anyways...might not have been working the 285s hard enough to get them up to their optimal temp (Pirelli Corsas are also a harder compound than medium hard compound R888s etc.)

madmax199

iTrader: (20)

It's possible and it has been done before. I run 315 X 17 V710 in my car but it's an XP car with cut fenders front and rear.

For a car that's not going to run wide/cut fenders and is not going to run tires wider than 285, IMO 18s are better in terms of fitment and performance(better response).

The reason to run 315 X 17 instead of the 315 X 18 is because:
1) the 18s have a taller overall diameter(26.4" vs 25.4" on 17)
2) save quite a bit of money(249 vs 326) per tire+ what was saved on wheel costs
3) the lower weight and shorter diameter of 315 X 17 gave them(on paper) a considerable performance advantage over 18s.

ForcedFedRS

iTrader: (23)

Thank you for correcting me madmax, I thought I might have seen it before on someones evo but wasn't positive.

jid2

iTrader: (62)

Holy monster truck batman. Is the increased ride height worth the extra meat? Why not wide body and get the height under control?

madmax199

iTrader: (20)

It only looks that way(mainly in the front) because there is 2" chopped off the fenders. Sitting on level floor, the front control arms are parallel to the ground and going lower in ride height would compromise handling and geometry (subteranean roll center and too high roll couple).

The car is low and if it was still on stock fenders(rears are also cut), the car would sit on the front wider race tires and low offset wheels and the rear tires would probably disapear under the rear fenders.

donour

iTrader: (6)

Custom trailing arms in the rear?

d