I understand the Volk Racing Limited Edition TE-37's for the 350Z are 19x8.5 in the front and 19x9.5 for the rears. What would be the correct tire sizes for these measurement wheels? I have searched the forums and found Volk Racing to use 245/35's for the front and 275/35's for the rears. I have also searched http://www.discounttiredirect.com's website for the correct plus sizing (which would be plus+2 in this case) and also confirms Volk Racing's choice of tire size...How do you go about mathematically estimating the correct tire sizes for larger wheels without comprimising the diameters (incorrect odometer readings)?

 

There's a formula for it where you can get a pretty close approximation of the actual size. remember the aspect ratio is a percentage of the tire width so if say you had a tire that was (for the sake of easy math cause i can't find a calculator right now):

200 - 50 / 18

the 50 (aspect ratio) is a percentage of 200 (tread width):

so the sidewall height is 100, which you then double cause there are two sidewalls in the tire height.

Then, you divide that number (200) by 25.4 to get inches, and add that to the rim size

so i spose a formula would be something like

((((width * aspect) / 100) * 2) / 25.4) + rimsize = overall_height_in_inches

If you want to stay in millimeters:

(((width * aspect) / 100) * 2) + (rimsize * 25.4) = overall_height_in_mm

Then you'd just compare the overall heights of each tire.

Remember also that different tire manufacturers differ in the widths and heights of their tires. Perhaps your best bet to get it really close would be to use a tape measure or something.

Someone should check me on this but i am pretty sure it's correct.

 

Use the tire size calculator. (Ignore how it says it's for Miata. Tires are tires.) Find out the closest match by trial & error.