papillion

Our plan is to order our car with base silver painted wheels and immediately swap them for forged aluminum wheels. These are the stock sizes for wheels and tires.

Wheel size: front: 18-inch x 8.5-inch (w/o Z51)
rear: 19-inch x 10-inch (w/o Z51)

Tires: Michelin® Pilot® Super Sport10 run flat
front: P245/40R18 (w/o Z51)
rear: P285/35R19 (w/o Z51)

Will the OEM Michelin tires mount to 18x9 and 19x10.5 wheels? Doesn't seem a half inch would create clearance issues or the wheels stick out too far. Just don't know if the tires designed for the smaller wheels will fit on the larger ones? Or if this would create handling issues?

Curtis A. Franz

Try a Tire Rack internet site or even Michelin.

B Stead

The stock tires on wheels 1/2" wider than stock but at stock wheel offset, would be very little risk. It just puts a slight outward slope on the sidewalls of the tires. And if there were a problem on the inside, down near the rim of the wheel, then a 3mm to 5mm spacer would be a mild mod. But get under the car with the stock setup and see what's available at static ride height. A 3mm to 5mm increase in outward wheel offset would be a mild mod.

But here are the setups to attempt:

18 x 9.5 with a 275/35-18
19 x 11.5 with a 325/30-19

19 x 9.5 with a 265/35-19
20 x 11 with a 305/30-20

And to my eye, attempt them at stock C7 offset.

If the tires stick out slightly then lowering the car can tuck them in. If inside clearance is a problem then offset trailing arms might solve the problem.

Actually, the 19/20 setup looks easy but does increase tire radius by 1/4".

Also, here is a tire fitment application that allows decimal input for width rather than require nominal input for width. That means that the calculations can work with tire section width dimensions or with tire tread width dimensions:

http://www.kbhscape.com/wheel.htm

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