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I've recently started autocrossing my '03 Z06 and want to upgrade to Falken RT660 based on a number of recommendations and reviews. Sadly, like many manufacturers now, they don't make the OEM sizes I need for stock rims. I'm considering 275/40 ZR17 for the front and 295/40 ZR18 for the rear because these are the closest matches I can find that aren't either too wide for the stock rims or significantly more narrow, which would sort of defeat the purpose of going with stickier tires. I have 3 concerns with this setup:
Clearance: The rear tires are 1.2" higher (sidewall, double that for circumference). Will they rub in a performance scenario when the suspension is fully loaded?
Vehicle Rake: The ratio of rear height to front height is slightly larger. Will this shift the weight distribution enough to change the handling characteristics?
Traction/Stability Control: I'm pretty sure I'm in the clear with this configuration, but I want to be certain I won't run into issues.
I'm currently on Pilot Super Sports and find them to be too hard for AutoX and difficult to heat up on short courses. Z06 stock rims are 17x9.5 and 18x10.5, which are a bit wider than non-Z06 C5s.
I've attached the RT660 tire size table for reference.
Last edited by CrashFender; Jan 17, 2023 at 05:32 PM.
Thank you for the response. It's great to hear from someone who's actually run the exact sizes I'm considering. I'm going to leave the thread open to post some after pics and race day impressions.
Good job! Yeah the Z06 fitments are tough, with the last post on your thread however you will be able to find good size combinations.
Originally Posted by CrashFender
Thank you for the response. It's great to hear from someone who's actually run the exact sizes I'm considering. I'm going to leave the thread open to post some after pics and race day impressions.
Definitely do that, will be interesting to see how they look. I'd go small side on the tire, compared to the wheels. Better for AX.
I’ve heard of going smaller on the tires, I just don’t understand why???
So, your saying, a 255 in the front, and a 275 rear???
Well, there's 2 trains of thought here.
1). 255's/9.5's
2). 275's/9.5's
The rear is good with 295's/10.5's, as this is what Chevy implemented with the Z06, in the first place. (Note: they also implemented 265's/9.5's, in front, which is already good).
The problem is, 275's are somewhat wide as recommended tire, for 9.5" wheels. A) According to TireRack, and B) According to physics. I.e., the tire will be "pinched", and "roll over", with spirited driving. Just a matter of pushing it. Relatively.
But many AX's however, don't care what the handling "feels" like, and what to get the widest tire on the wheel as possible. Some of them are actually fast.
On the street, which personally is where I do my driving, I like the slightly "stretched" narrower tire on the wider wheel. Better response. More consistent handling. Who gives a **** what it looks like.
Tirerack tests BOTH 265's, and the 275's, on 9.5"'s...however exact theory remains - you'll be pushing it with 275's, and it won't be that sharp. There's a reason GM went with 265's. Ymmv.
Tirerack tests BOTH 265's, and the 275's, on 9.5"'s...however exact theory remains - you'll be pushing it with 275's, and it won't be that sharp. There's a reason GM went with 265's. Ymmv.
GM went with 275s on the Camaros that wore 9.5" rims.
Not sure what exactly you're referring to here, but I have my doubts they decided a 275 was too wide for a 9.5" rim. More likely they were targeting a specific stagger, but really anything is speculation. If a 275 wasn't too wide on the Camaro, it likely wasn't too wide for the Corvette, had to be something else.
Not sure what exactly you're referring to here, but I have my doubts they decided a 275 was too wide for a 9.5" rim. More likely they were targeting a specific stagger, but really anything is speculation. If a 275 wasn't too wide on the Camaro, it likely wasn't too wide for the Corvette, had to be something else.
Upsizing Tires
