EdwardGT

I found a local deal for $400. There's always sets on ebay and criagslist.

14901490

For now i plan to stay with the stock wheels which are 17 " x i believe 8 "?
What is the max width u guys are using for a road course situation - Watkins Glen?

- NOT a drag strip .
Thanks

EdwardGT

I used to run 245/40/17's on my STi's 17x8's with great success. This particular tire size would be too short for the 'stang; but I just wanted to give you an idea of what width you could run.

-Edward

14901490

why do you say its too short ?

Sleeper_08

I'm not sure about the Glen but at Mosport with the 285/40/18s we run out of revs in 4th gear on the back straight. Shifting to 5th does not work as it is an overdrive ratio so it is best to leave it 4th and just run at the rev limit! If we went to a smaller tire it would be even worse.

EdwardGT

235/55/17 is the stock tire size. This is a 129.25mm sidewall height. 245/40/17 yields a 98mm sidewall height. Thus, this tire size is over 2" shorter overall.

-Edward

14901490

Dont want to seem stupid but do i need to stay with a 55 height ? & why

EdwardGT

No, you don't need to stay with the same aspect ratio. However, unless you want to change the effective gear ratio, stay with the same sidewall height, i.e. section width x aspect ratio.

-Edward

Sleeper_08

To not affect the maximium speed in each gear you want to get a tire that is the same diamter as the originals. For example a 285/40/18 is the same diamter as a 255/45/18.

To see what diameter a given tire is you can use www.tirerack.com and choose the brand and size of tires and then check out the specs for the overall diameter. Here is their page for the BFG KDW2s;

http://www.tirerack.com/tires/Spec.j...irePageLocQty=

Argonaut

Um...what is the question here?

You start this thread asking for advice on 18 in vs 17 in. Then later you state you will be staying with the stock 17s. whats up?

My 2 cents - having been down the 17 in road (17x9 with 275/40 rubber) I wouldn't do it again for several reasons: The overall diameter is too short, which leads to gearing issues (as noted) and lack of ground clearance (unless you ONLY run on the track, but then even on a track like Shenandoah you still scrape); you leave yourself few options on brakes - if and when you decide a BBK is needed. The rubber really isn't cheaper anymore IF you buy used. Many racing series are switching to 18 in rubber, this leads to lots of scubs being available, like R888s for 100 each. They are slightly lighter though. If I had to do it again, it would be 18" for me.

Couple more random thoughts: I know Sleeper likes his GT500 take-offs but most dedicated track junkies have a low opinion of them. They are bottom of the barrel Brembos. Both the NT05 and the XS are pretty new. Both are receiving very good press. Just so no one is confused: Nitto 555 and the 555RII are in completely different classes. The RIIs are treadwear 100 R-Compounds and, while not exactly R6s, are very sticky. I've used them and have been pretty impressed, the only drawback is they are directional.