I'm using a 1981 Camaro 10 bolt on my '50 3100. I'm trying to determine what offset/backspacing wheel I can get between the wheel mounting surface and the fender. I have 5" from the mounting surface to the inside fender surface/bed side...I have just under 6" from the mounting surface to the rolled lip on the outer side of the fender. I want to use at a minimum an 8" wide wheel. I would like to use a 255/70 tire on a 18" wheel. I'm trying to get as much wheel and tire under the fender without tubbing the box. I've never had to measure offset/backspacing. I want to be correct when I make my purchase...too late then if I was wrong! I assume that 1/2" to 3/4" would be enough clearance on each side? I have to believe you high performance "bolters" can advise me correctly.
I have a '78 Camaro rear end with 15 x 7 wheels. Wheel backspace is 4.25". Tires are 205 75R15.
I occasionally get a slight bit of rubbing on the box sides - just enough to make a mark without removing the paint. I don't think that tires 50 mm wider than what I have now would fit without modifying the fenders. (I'm presuming that the 8" wheels will have a 4.5" backspace - you need to confirm)
Last edited by Gord&Fran; Thu Jul 29 2021 11:22 PM.
One major drawback to a tire that wide is going to be VERY squirrely handling every time it rains. There's just nowhere near enough weight on the back end of a stovebolt pickup to keep a wide tire planted tight to wet pavement. Maybe if you made the bed floor from 3/8" steel plate- - - - - - -!!!!!! Jerry
"Freedom's just another word for nothing left to lose" Kris Kristofferson
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Here are the front / rear weights on my stock 53 3100 with no driver. I'm running a Frankland quick change with 12.88 Wilwood disk, Gleason Torson diff. I had Frankland (and Wilwood) make it so my mounting surfaces would be the same as stock. I also don't want to tub the bed. In most classes I'm limited to an 11.5" tire and want to run a 10" to 11" tire. I'm getting a price worked up now on widening the fenders 2" and having an inner fender liner made from donor fenders. If I have a tire come apart I don't want it to ruin my paint. I'll let you know when I get a price. My skill level is not that good to do it myself. I was very surprised that my truck was so well balanced. I have always been told that pickups were light in the back. With todays all weather tires I think I will be fine. I don't plan on "racing in the rain" which is a great book by the way. Thank you for your time.
MiraclePieCo...After reviewing the tire chart, I believe I'll stick with a 255/50/R18 for a rear tire. I like the fact that the width of the tire is 10"...should fill up the fender fine AS LONG AS I GET THE RIGHT OFFSET ON A 8" WHEEL!
I'm guessing your 255/50/18 will be perfect - as long as your wheel has the right offset/backspacing. Try the wheel on the truck first without the tire; as long as you haven't mounted a tire the wheels are still returnable.