Rear wheel and tire size (again)


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By MoonShadow - 13 Years Ago
Did a search and didn't find what I needed. I know this has been asked and answered many times but? On my 56 Ford Fairlane, I have a set of Mopar 15"X7" wide wheels for the rear. Havn't measured the offset and they are in storage. Anyway, lets say they are 3" offsett. Finally the question, what is the largest width tire that I can fit on the rear without massaging the body etc? Thanks, Chuck
By Jerome - 13 Years Ago
I have a 56 Fairlane Town Sedan with a stock Ford 3.89 ratio rear end. I am running custom 5" backspaced Cragar 15"x8" rims with P255/60R15 T rated Dunlop G/T Qualifier 27" diameter tires with an 8.2" tread width. I had to replace all my leaf spring bushings, fabricate a panhard rod and trim off some frame protrusions in order to keep the rear end sufficiently centered to avoid tire scrub when turning. My 56 original equipment tire diameter was 27.5". The tires are big enough that I have to jack the car as high as the jack will go to wiggle the tire out of the wheel well. Carry some good tire chocks in your trunk for changing a tire if you go this far.

If I fine tuned the wheel backspacing more, went to a better Watt's link rear centering design and limited axle vertical travel, I could probably stuff a pair of Mickey Thompson ET Street 27x10.5x15LT tires under my ride. But, I'd likely need a way to undue the axle drop restriction to change them.

My spreadsheet of Joe Pettit's chassis tuning model calculates 354 ft-lbs of engine torque to break my right rear Dunlop radial tire loose (3.89 ratio rear end, 2.49 ratio 1st gear and 0.8 radial tire friction coefficient). With my traction bars and current 322 cubic inch y-block tune, I have all the traction I need without ET Streets.

Jerome

By MoonShadow - 13 Years Ago
Jerome,

Thanks for the response. I'll do some clearence checking and see what I can fit. By the way if you use Truck shocks, I think part number Gabrial Ultra G6339, they are longer and will allow the rear end to drop further when you jack it up. Makes tire changes on a lowered car easier. No change in ride height or comfort. Chuck

By Canadian Hot Rodder - 13 Years Ago
Chuck, I my Explorer wheels on my 56 are a 4" offset I believe and I am running 225 / 60 / 16 's with the 57 9" in back. This gives me about 1/2" clearance on either side of tire in the wheel well. Hope this helps. Smile
By Talkwrench - 13 Years Ago
I used those truck shocks and they are rubbish.. I could of had a dud set because when I got them I could pull them in and out real easy..didnt seem right . Recently I took them off and put the old shocks back on , heaps better.
By MoonShadow - 13 Years Ago
Sounds like a dud set. I've had mine on for a year or so now and no problem. Chuck
By speedpro56 - 13 Years Ago
Chuck, On my 56 Tbird straight line my wheels are 4 1/2 back spacing 15x7.  Tire size 235/60/15s and this going down the track. Everyday driving not wanting to hear tire scrubbing in the curves I'm running wire wheels with 4 1/4 back spacing 16x6 and you can run the 4 1/2 back spacing but tire size comes down to 225/70/16s. I've run these same tires and wheels on my 56 sunliner with no issues at all under the same circumstances. Running the 235s you start getting into problems of scurbbing here and their and it doesn't matter if it's 15s or 16 inch wheels in hard curves. Just my 2 cents worth.