jpo06gt

I've got stock 17's with stock 235/55 Pirelli's. I can't decide whether to switch to 18's or not. I don't need a bigger rim for appearance. I only want a better cornering wheel and tire combo. So, which size is better for corners, and more importantly -- why???

I would appreciate any recommendations along with a reasonable explanation to back up the opinion. Thanks!

Norm Peterson

If you're going to stick with 27" tall tires there's more to choose from in 18" (255/45, 285/40). 275/40-18's are also at least possible at ~26.6" tall (and I think that some members are actually using these). Off the top of my head the better cornering 17" rubber comes in sizes that are an inch shorter than the 275/40-18.


Norm

Argonaut

Trade offs: 17" rubber is cheaper, weighs lessand is probably the most used size for Road Track and AutoX.But there are more options available in 18" and ~27" diameter. As far as which "performs" better -in a recent issue of SportsCar magazine they did some testing of two Hankook R-S2 tires: 205/50/15 vs 205/45/16. Roughly the same overall diameter - its essentially a test of high profile and narrow VS low profile and wide. The 15" performed better in acceleration and braking (due to increased sidewall flex) while the 16" performed better in turn in and transitions. So....back to our cars. Options:

< 27" diameter 17s: inexpensive, great in corners (assume summer only type tire). Traction off the line is poor. Makes for unsightly gaps between fender and tire.
>= 27" diameter 17s: inexpensive, stock, several good all around tires available, better start/stop traction (given the same model tire)
~27" diameter 18s:costs more for the same model tire, lots of options for both all around and high performance. More rotating mass. Less start/stop traction (less sidewall).

I could go on but hopefully made my point - there is no right answer. Each option has trade-offs. Keep the 17" rims and put super sticky, low treadwear street class race tires on them, get a set of 18" rims and put DD rubber on. Then you can have the best of both worlds

Nuke

I'm definately more sure-footed in corners with my 275/40/18's then I was with the stock 235/50/18's, for what it's worth. I have the stock 18 x 8.5 fan blades for sale. PM me if you're interested.

Margarita Girl

I switched out my stock 17" rims/tires for 255/45/18 front, 285/40/18 back.

Very happy with the Toyo Proxes T1R Summer.
They stick to the road much better than the stock Pirelli all season.

ensign_lee

Wait. You can put 18" tires on 17" rims?

157dB

17s versus 18s with the same rolling diameter or Revs/Mile.

18s have a smaller sidewall and deflect less during turns than 17s
but transmit every bump to the driver more so than 17s would.
But on 17s the tread rolls under more during hard cornering than
would 18s with the smaller sidewall.

Margarita Girl

No.

Nuke

Duhhhhhhh....

I nearly choked on my sandwhich with that one...