clarkster009

http://www.1010tires.com/WheelOffsetCalculator.asp

If I look at this with a 17 x 9 +45 vs a 17 x 8 +45 it looks like the 9" wheel is pushed out by 13 more mm. So it seems to me that the 8" would be easier to fit without having rubbing.

But this from the fitment guide says:

Here�s the important thing: Since the offset is measured from the center of the wheel, the location of the tire tread (the part that can rub) does NOT depend on the width of the wheel, only the OFFSET of the wheel. What does this mean? It means that you can have two wheels, one 7 inches wide, and one 8 inches wide, and if the offset of the two wheels is the same, the tire will be in the same place relative to the fenders. The tire�s side wall makes up the difference between the 7� and 8� wheel. But the tread will be in the same place.

So is that saying that a 17 x 8 +45 with a 225 tire would be the same as a 17 x 9 +45 with a 225 tire in regards to rubbing? Or would the 17 x 8 be less prone to rubbing?

Dreaming_S2k

It actually depends.

I agree it's a little confusing, but you have to remember this: The tire might stay in the overall same spot, but you'll also get stretch with a wider wheel. I think in your example, what it really comes down to is ride height. If you're slammed, suspension travel will make it easier for the 9" to rub.

I don't know that I ultimately agree with this, but they're kinda speaking in the sense that they're not counting really large stretches. Probably nothing more than something like a 225 on a 9"

Think of it as offset against the width of the tire. So if your tire is 9" wide, and the wheel offset is +45, then that will be what you'll need to take into account. What gets tricky is that you'll likely have to look up the actual spec of the wheel, and not just convert the mm sizing into inches, since some tires run differently. (example, star specs run "large" for their sizing)

You still can't forget about wheel width though. All 3 things matter, you just gotta find what you like and what works.

clarkster009

^^ Thanks!

So I guess that boils down to the question...

I have a 9" +45 wheel on the rear right now with a 255 tire. If I switched to an 8.5" +45 wheel with the same tire, would it have less a chance of rubbing? In other words, since it is 8.5" it should be sunk in more correct, so I would think this would hold true.

Jim@tirerack

You would have more clearance with the 17X8.5 wheel and keeping the same offset. You are actually going to gain about 1/4" clearance at the fender.