mopar420
Active Member
I have a 74 duster with a 393 stroker and a 4 speed and im wanting to put 18s on the front and 20s on the back? Im wondering if i could get some help on backspacing and it it would be better to go with just 18s!
Need help with rim back spacing?
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Claudius
Well-Known Member
There is another thread in the "Tires & Rims" section that discusses the backspace topic in detail. I could not immediately locate it.
Per previous advice I have read at this site, I will probably just take a straight edge and hold it directly against the wheel hub. From there, measure straight in (toward the middle of the car) throughout the entire range in which the wheel will turn.
The narrowest measurement is the one to work with. (ie: leaf spring for rear wheels). You have to allow space for clearance from the sidewall of the tire; this is up to your comfort level and I have seen some people with very negligible spacing. You also have to factor in the section width of the tire you want to use; that is given with the tire specifications. The leftover amount should be the allowable backspacing.
On the front, your primary concern will be contact with the upper control arm, both running straight and when you turn the steering wheel.
If you want to purchase something specifically for the purpose of checking backspacing and wheel diameters, Summit Racing has the following for $70.
http://www.summitracing.com/search/?keyword=PHP-01201&dds=1
Per previous advice I have read at this site, I will probably just take a straight edge and hold it directly against the wheel hub. From there, measure straight in (toward the middle of the car) throughout the entire range in which the wheel will turn.
The narrowest measurement is the one to work with. (ie: leaf spring for rear wheels). You have to allow space for clearance from the sidewall of the tire; this is up to your comfort level and I have seen some people with very negligible spacing. You also have to factor in the section width of the tire you want to use; that is given with the tire specifications. The leftover amount should be the allowable backspacing.
On the front, your primary concern will be contact with the upper control arm, both running straight and when you turn the steering wheel.
If you want to purchase something specifically for the purpose of checking backspacing and wheel diameters, Summit Racing has the following for $70.
http://www.summitracing.com/search/?keyword=PHP-01201&dds=1
1968FormulaS340
Well-Known Member
You will really be shrinking your contact patch with 20s unless you are doing mods to get a wider wheel under the car.
Different brake and suspension setups can change any wheel measurements especially when you are pushing the envelope on sizes.........dont take opinions/advice without measuring first.
Several tools are on the market to help measure, percy's and mountmate come to mind right off hand.
Several tools are on the market to help measure, percy's and mountmate come to mind right off hand.
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