smuddy
Well-Known Member
- Thread starter
- #1
After reading seemingly hundreds of posts about backspacing, offset and rim width, I'm finding that opinions are all over the place! But after playing around with a lot of numbers with this site: http://www.rimsntires.com/specspro.jsp?item=Wheel-Tire size comparer&sw1=285&ar1=70&bd1=17&rw1=7.5&et1=44&text1=Sample 1: Hummer H2 wheel&sw2=315&ar2=70&bd2=17&rw2=9.0&et2=12&text2=Sample 2: Honda Civic wheel
It seems that backspacing doesn't really matter on whether or not a wheel/tire will fit without rubbing the suspension. To me, it seems more about the change in offset coupled with the change in tire width. Rim width doesn't matter one difference. If you have a rim that is 7.5" wide and one that is 9" wide using the same offset of say +12, the 9" rim will have more backspace, and yes, the rim will both stick out further and be closer to suspension than the 7.5" rim, but if you are relating this to the same size tire, say a 315 width, then where the tire is will be in EXACTLY the same location in relation to where it sticks out past the fender and how close it is to the suspension even though one has a backspace of 4.7" (7.5" rim) and the other has a backspace of 5.5" (9" rim).
So why is everyone all over the place with this?
The mopar beadlock wheel on the mojito jeep at the LA autoshow has a +12 offset and it's an 8" wheel with an effective backspace of 5". So it would seem that any rim width would work as long as it has +12 offset even though it will change the backspace for the rim quite a bit since, it won't change the proximity of the tire to the suspension components on the inside of the wheel.
I was looking at a 17x9 wheel with +12 offset to use with 315 70 17s and that site says I'll have more clearance on the inside of the tire by about .5" so I should be fine, even though it has a backspace of 5.5".
Thoughts?
It seems that backspacing doesn't really matter on whether or not a wheel/tire will fit without rubbing the suspension. To me, it seems more about the change in offset coupled with the change in tire width. Rim width doesn't matter one difference. If you have a rim that is 7.5" wide and one that is 9" wide using the same offset of say +12, the 9" rim will have more backspace, and yes, the rim will both stick out further and be closer to suspension than the 7.5" rim, but if you are relating this to the same size tire, say a 315 width, then where the tire is will be in EXACTLY the same location in relation to where it sticks out past the fender and how close it is to the suspension even though one has a backspace of 4.7" (7.5" rim) and the other has a backspace of 5.5" (9" rim).
So why is everyone all over the place with this?
The mopar beadlock wheel on the mojito jeep at the LA autoshow has a +12 offset and it's an 8" wheel with an effective backspace of 5". So it would seem that any rim width would work as long as it has +12 offset even though it will change the backspace for the rim quite a bit since, it won't change the proximity of the tire to the suspension components on the inside of the wheel.
I was looking at a 17x9 wheel with +12 offset to use with 315 70 17s and that site says I'll have more clearance on the inside of the tire by about .5" so I should be fine, even though it has a backspace of 5.5".
Thoughts?
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