C6CLAYTON

I’m currently building a c5z street car and wanted to verify the largest tire size for stock wheels.

275/40/17 front
315/30/18 rear

ive read lots of comments throughout the forum and this seems to be the most common scenario. TIA

Tsumi

Best bet would be to check with the tire manufacturer. They typically will list approved wheel widths. As long as your wheels fall within that range, they should be fine. Occasionally, tire manufacturers can have different approved widths even with the same size tires.

The sizes you have listed are marginally taller than stock sizes, so unless you're slammed, you should be fine as far as diameter is concerned.

C5Z stock widths are 9.5" for the front and 10.5" for the rear.

Gordy M

Your front tires have a 25.6" diameter and the rears are a 25.5" diameter. You will have issues with active handling with this set up. You would need a 275/35x17 front tire for the nannies to be happy or a 315/35x18 rear tire in your set up

C6CLAYTON

So would your recommended sizes be safe to purchase and still clear without issue?

Tsumi

Whoops, didn't actually run the calculations, my bad.

Gordy M

You are right I it should have been TC. Running same size tires and having the nannies kick in is more a problem with tires with better traction. I have run same diameter run flat tires on all 4 wheels without any incident and have run same diameter Bridgestone RE71 tires cruising down the highway and have had the nannies kick-in changing lanes. Driving to a local event on Hoosiers at speed, the nannies would kick in with any with almost any steering input.