Largest tire size on '76 Sprint

vega_guy_76 · Posted: Thu Dec 11, 2003 5:05 am Post subject: Largest tire size on '76 Sprint

I'm planning on getting new rims and tires for my '76 Sprint within the next two or three months. I would like to know the widest possible tire I can fit on the front and rear. I am not concerned with tire height at all, as I've got 28" tall tires front and rear. I will be going to a 26" tall tire front and 27" tall on the rear. Is it possible to fit a 315/40/17 out back? And a 255/45/17 up front? My only concern is to have the tires rub. On the rear I'm thinking I will have to mini-tub it to fit this kind of a tire. I havn't gotten under it yet to do any measuring as my job has me away from the house about 12 hours a day.

Charles
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1976 GMC Sprint SP, Buick 455, TH400, 2.56 gears--- 14.640 @ 93.22mph 2.234 60'
1976 Chevy Vega Wagon, Buick 3.2L V6, TH350, 2.56 gears
1977 Chevy Monza 2+2, 350, TH350, 2.73 posi rear
2000 Dodge Dakota SLT 4x4, 3.9L V6, 5spd Manual, 3.55 gears

ElkyPete · Posted: Mon Dec 15, 2003 7:48 am Post subject:

I would think that, with the right backspacing, you'd be able to get all of a 50 series under the fender well on 8" maybe 9" rims. If the sidewalls were spongy you'd end up with a rubbing problem in corners. So you could have to go with those rubber bands they call tires for the extra strength in the side deflection of the tires.

9" Rim with say about 4.25" backspacing would leave you with something like 1/2" between the frame and the rim bead on the back. This is assuming the manufacturer considers the offset into the backspacing or there is a Zero offset on the rims.

Some tire places will check the setup for you so that you get what you want or understand why you can't have it. You need about 1" clearance between the rim bead and the frame in the back for sidewalls and deflection. The front tires are a different story they have a completely different setup to get around.

Front tires will still have to deal with sidewall deflection but all the way left/right (stops) you can rub the frame, the wrong sized rims can also rub on the brake caliper or hit the steering linkage, brake line bracket ...

I think the 76 used an 11" rotor on front. So anything above say 15" should be able to clear most obstacles with a decent backspacing. I don't know if I'd go past a 4" backspacing on the front.

Its just an opinion.
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1972 El Camino Custom 400
1976 El Camino Classic
1980 El Camino Super Sport
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vega_guy_76 · Posted: Fri Dec 19, 2003 4:05 am Post subject:

I did some measuring last weekend and found that I could easily fit a 10" wide rim on the back. I measured 14" from inner most portion of the wheel lip to the wheel well. So I figure a tire with a 12.50" section width (not tread width) would be perfect. I'll be doing some measuring of tires at the local Les Schwabs (pacific NW guys know where I'm talking about). I'm now thinking that I will stick with 15" rims instead of to 17"s I was thinking of. I need all the sidewall I can get to hook up this beast.

Charles
_________________
1976 GMC Sprint SP, Buick 455, TH400, 2.56 gears--- 14.640 @ 93.22mph 2.234 60'
1976 Chevy Vega Wagon, Buick 3.2L V6, TH350, 2.56 gears
1977 Chevy Monza 2+2, 350, TH350, 2.73 posi rear
2000 Dodge Dakota SLT 4x4, 3.9L V6, 5spd Manual, 3.55 gears