Correct tire width for each wheel width

[DarrenDriven]

Hey guys, I am improving the Wheel Directory topic once again with another tidbit for new wheel buyers.

I need to know the correct tire width for a flush fitment for each wheel width.

WHEEL (inches) = TIRE (mm)
7.0 = 215
7.5 = 225
8.0 = 235
8.5 = 245
9.0 = 255
9.5 = 255
10.0 = 265

I could probably look it up, but I am crazy busy and I know that some of you have this information handy... or have some extra time.

[dave99rt]

there is not a clear cut answer for this.

you should be looking at section width (sidewall to sidewall) and what width wheel it was measured on.
it will marginally change with changes in wheel width.

a 215mm tire will not always be 8.46"
high performance tires tend to be wider than size would indicate.

[empower-auto]

I have 215 Cooper RS3's with big shoulder blocks on the front of my car, and the stock 215 Michelin Primacy's on the back. The fronts fill out way better. (look better too)

[TheRipler]

There may be some general rule of thumb, but it's mostly going to depend on the rim width range of a specific tire.

http://www.tirerack.com/tires/tirete...e.jsp?techid=7

Actual Tire Section Width is Dependent on Wheel Width

All tire sizes are assigned specific rim widths upon which they are measured (measuring rim), as well as can often be mounted on slightly narrower or wider wheels (rim width range). Therefore, it is important to note that actual tire section width will depend on the wheel width the tire is mounted on. The rule of thumb is that tire section width changes by 0.2" for every 0.5" change in rim width, being reduced if mounted on narrower then measuring wheel and increased when mounted on wider wheels.

[Entropy]

This is a very subjective aspect of wheel/tire fitment. Some people prefer a somewhat stretched look, some people like a bulgy look, and some people like it to be "square" (like me!). Another thing to think about is that most "track" tires have oversized treadwidths (i.e. a 215 Hancook RS-3 has the tread width of a regular ol' 225, maybe even a 235).

In general, I would say:
7 =215
8 = 225-235
9 = 245-255 (9.5 would be perfect for a 255)

[Razing]

I have 18"x8" and 245/35s fit perfect on them

[DarrenDriven]

Thanks Entropy... I'm looking for a square-fitment guideline that I can post for people who are clueless and need to order tires. I'll put your numbers in the first post and see if anyone wants to argue about it.

[DarrenDriven]

I went with this... anyone want to improve the accuracy?

7.0 = 215
7.5 = 225
8.0 = 235
8.5 = 245
9.0 = 255
9.5 = 255
10.0 = 265

[Stu baru]

That looks about right as a mid-point number based on what I've been looking at for Goodyear performance tires and their fitment ranges.

[MattR]

It can differ based on Diameter and Aspect Ratio.

Using Yokohama Advan AD08's as an example tire...
225/45-17 would like a 7.5" wide wheel
225/40-18 would like an 8" wide wheel

Both 225s, but with different wheel width rec's. It could also differ from manufacturer to manufacturer, but maybe separate lists for 17s and 18s is in order?

[DarrenDriven]

That is not a bad idea... but I will word this as a guideline only and not a definitive definition of which tire is "correct". If we suggest 17's and 18's then we need 16, 19 and 20?

Maybe it is just too complicated to even provide a guideline? I figured something simple would help newbs feel better about their wheel and tire sizing -- even if it isn't absolutely perfect.