I know this question has been answered before and I have looked through the wheel data base but what is the correct backspace I need to put 295/50/15 or 295/65/15 in my 67 chevelle I noticed that some people are using 15x8 with 4 7/8 backspace and 15x10 with 5.5 back space wich is the best way to go
my goal is to put the largest tire possible in the rear and I am willing to do what ever mods I have to to make this work(rolling the lip ect...)
please help me out because I dont want to waste money on something that doesn't fit, btw I have a fab 9 rear end with stock length.

I am running 295/50-15 in back of my 66 (stock 66 12-bolt), with no lip mods... I have a 15X8 rim with about 5" of BS... Fits well, but tight...

I spoke with a tech from a tire company (BFGoodrich), and they said the 8" rim was better for straight-line traction, and the 10" rim was better for handling (or vice-versa, its been a while), but the differences were marginal (theoretical?) at best... If really worried about handling, you should go to a 17"+ tire and wheel...

There MIGHT be some clearance issues between the lower part of the shock absorber and the wheel when using the deeper BS...

I do NOT agree with the 5.5" BS on the 10" wheel... Might work, but I think it should be closer to 5.75"+... 2" wider wheel should need 1" additional BS to have the rim centered the same IMO, I'd want the tire as far from the outer lip as possible... Even if the inside rubs, its flat sheetmetal, but the outside lip will cut into the sidewall. Plus, the cuts will be visible when people are looking at your car...

Even IF you trim the lip, there is a body crease above the lip that sticks out almost as much as the lip (about 1" above the lip). If you trim for clearance, the tire may still rub here (lowered, and/or with some buddies in the back seat, etc)...


The 10-inch wheel will also cause the sidewall to protrude slightly more, reducing clearance. The tread width (contact patch) is the same regardless of which wheel you choose (8" or 10"), and both sizes are within the recommended range (at least for BFG specs)...


Be sure to measure both sides, as sometimes they aren't exactly equal (body shifted, etc)...

thanks tony for your good information,just wondering if you went with a 5.5 back space and put shims? because I noticed welds and other only offer the backspace in 4.5 5.5 ect..
thanks
steve

Running a 15x10 w/5.75" backspace is going to put the inner rim really close to the lower shock mount,depending on production tolerances. Taller diameter wheels don't have this potential problem. Just something to consider,Steve.

thanks tony for your good information,just wondering if you went with a 5.5 back space and put shims? because I noticed welds and other only offer the backspace in 4.5 5.5 ect..
thanks
steve

I actually have "aftermarket" rally wheels... I custom ordered the offset I wanted... I actually ordered incorrectly, and had some minor rubbing on the inside, so I run a thin spacer... I took into account the spacer thickness when noting what the "backspace" is... Actual backspace on my wheels is about 5.25"+, and my spacer is 0.219", making the effective BS about 5"... I have about 1/8"+ clearance on the inside and about 3/8"+ on the outside, so I don't think a 4.5" BS would fit at all, without trimming...

You might be able to get the 5.5" BS and run a 1/2" spacer... I have run the 0.219" spacer (7/32" from Mr. Gasket) for 10+ years, even took it to the dragstrip... No problems (you might have to get longer studs to use a spacer, to ensure proper )... Personally, on a cruiser, up to 1/2" spacer would be okay (thicker if it was hub-centric maybe). I don't think I'd want to go thicker... If I was racing alot (especially with a sticky tire, hard launches, etc), I don't think I'd even want the 1/2". Its really just your comfort level (a brake drum and slip-on rotor are like spacers... Also, better quality studs would be on my list...

The studs work on tension and shear, but with a thick spacer, bending might also come into play, and thats not good, IMO...

I actually have "aftermarket" rally wheels... I custom ordered the offset I wanted... I actually ordered incorrectly, and had some minor rubbing on the inside, so I run a thin spacer... I took into account the spacer thickness when noting what the "backspace" is... Actual backspace on my wheels is about 5.25"+, and my spacer is 0.219", making the effective BS about 5"... I have about 1/8"+ clearance on the inside and about 3/8"+ on the outside, so I don't think a 4.5" BS would fit at all, without trimming...

You might be able to get the 5.5" BS and run a 1/2" spacer... I have run the 0.219" spacer (7/32" from Mr. Gasket) for 10+ years, even took it to the dragstrip... No problems (you might have to get longer studs to use a spacer, to ensure proper )... Personally, on a cruiser, up to 1/2" spacer would be okay (thicker if it was hub-centric maybe). I don't think I'd want to go thicker... If I was racing alot (especially with a sticky tire, hard launches, etc), I don't think I'd even want the 1/2". Its really just your comfort level (a brake drum and slip-on rotor are like spacers... Also, better quality studs would be on my list...

The studs work on tension and shear, but with a thick spacer, bending might also come into play, and thats not good, IMO...

I'm confused now,Tony. With what wheels are you using the above figures? 15x8 or 15x10?