Rims and Tires on Bell 92 TT

[NSSEXTC]

I recently purchased a Bell TT 92 white on black NSX and am wondering if I should keep my extra set of rims to put on the car or sell them. The rims are 18x8.5 and 18x9.5 chromed Enkei RP-01's. My major questions are, will both rims being 18's instead of using a 17/18 combo make a huge difference in performance of the car? and what size tires would you recommend. ATM the fronts have 245/40/18's. I am wondering if those tires rae unusable for the NSX due to rubbing (the tires are Nitto 555's), and the rears rae 275/35/18's (also Nitto 555's). Thanks

[nsxtasy]

These tire sizes are terrible for the NSX. For example, the TCS (traction control) will not work at all.

The TCS depends on the ratio between the outer diameter in the front and the outer diameter in the rear being close to that of the stock tire sizes (205/50ZR15 and 225/50ZR16, respectively). If the ratio changes by more than 4 or 5 percent, TCS will not work. In your case, you are using a front tire whose outer diameter is 11.5 percent larger than stock (wow! that's HUGE) and a rear tire whose outer diameter is 2.9 percent larger than stock, so the ratio is thrown off by roughly 8 or 9 percent. Definitely no good.

If you need to compare tire sizes, there's a useful tire size comparison function at http://www.powerdog.com/tiresize.cgi

[scott]

The rims will work as long as the offset is OK and lug nut spacing. Even then you could run a spacer. Check the FAQ.

for 18' the tires up front could be 225/30/18 and 285/30/18 rear. This would be 1% larger in front and 0.5% smaller in back. The main thing on traction control is to keep differental size below 5%. I have my fronts and rear oversized by 3%/4% and my traction control still works because it is only 1% difference.

Change your front tires to 225/30/18 and burn the backs off. They will be gone soon enough! The front width odf a 225 is 8.86" which is not much wider than the 8.5" rim width. It looks like a good swag is to oversize the tire width by 1.5" over rim width IMHO.

[Chris@SoS]

Very crappy tire sizes indeed.

My tech has also had the RP01's crack on the track, they are weak in structure and composition, which the chroming process most likely did not help.

-- Chris

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Chris Willson
www.ScienceofSpeed.com (http://www.ScienceofSpeed.com)
www.NSXClassifieds.com (http://www.NSXClassifieds.com)

[nsxtasy]

Change your front tires to 225/30/18 and burn the backs off. They will be gone soon enough!

This will work. Of course, you'll want to buy those front tires in the same model (the "crappy" 555) so that the car stays balanced. If you do this, once you use up the 275's on the rear, you can then replace them on the rear with the 245/40-18 tires you already have, and use them up, too.