i have weld prostar rims 15x10 with 5.5 back spacing. im wondering if anybody knows the BIGGEST tire i can possibly fit in here with STOCK wheel wells. if ANYBODY can help me---it's be a HUGE help......thanks a lot.
vehicle is a 1970 chevelle with STOCK wheel wells.


kevin

Unfortunately, I've heard & read many opinions on this one & am trying to find out myself. I currently have 275/60 15 BF Goodrich on stock rims on my '72. I am looking to buy a set of Torque Thrusts and was told I could safely fit a 275 or even a 295 on a 10" rim in the rear with a 5 1/2" backspace. I read another story where someone said that a 275 on a 10" rim was OK & no modification was required but a 295 requires the fender lip to be rolled under. My friend runs an 8" rim with 5 1/2" backspace with a 275 tire on his '70 & swears there isn't enough room for a 10" rim. He said he can only fit a finger between the fender on the outside & the frame on the inside & if he puts 3 people in the back it will occasionally rub. If you get a legit answer on this one PLEASE send me an email. graemlins/clonk.gif bhess64@hotmail.com

I was running 275-60/15'a on 15 x 10's w/ 5" BS on my '69 (see pics in sigature). I have since switched to 15 x 8's w/4.5" BS all the way around. Made the change mainly to get a better footprint from the 275-60 w/ less air pressure. A 5.5" BS should have allowed a 295-50/15 with no problem, depending on ride ht. Can't imagine the 69 & 70 are that much different in overall dimensions.

So the key here is a 15 X 10 rim will work at a 5" or 5 1/2" backspace but if you want to go from a 275/60 to a 295 you need to switch to a 50 series tire? The stock rims on my '72 are 7" with a 4 1/2" backspace. I am running a 275/60 on the rim without any clearance issues. By changing to a 10" rim I would assume it would only change the width of the tire at the rim, not at the tread of the tire. I guess the best thing to do is to measure how much room I have on the inside and outside of the tire and use that to determine how much backspace I will need. If I have more room on the inside than on the outside than I will need to add more backspace. The only place I think a problem may exist is the tire hitting the exhaust pipe. From what I remember that was the closest thing to the inside of my tire.

You don't have to switch to a 50 series, but there are no production 285 or 295 60 series tires for a 15" rim. Regarding rim widths, 8" rim with 4.5" BS and a 10" rim with 5.5" BS both have the same centerline and are considered "0" offset. The tire gets centered over the face of the drum/rotor.

Stock wheel wells, Moroso Trick rear springs, QA1 adjustable shocks.
Tires are 275-60/15 M/T Drag radials on 15x10", 5.5" BS Weld Prostars...plenty of room.
Same size/type wheel...Hoosier 10.5"x15x28" slicks also fit great.

http://www.chevelles.com/showroom/BillsCamino/70chevellerear.jpg

Originally posted by bobs72ss:
[QB] So the key here is a 15 X 10 rim will work at a 5" or 5 1/2" backspace but if you want to go from a 275/60 to a 295 you need to switch to a 50 series tire? The stock rims on my '72 are 7" with a 4 1/2" backspace. I am running a 275/60 on the rim without any clearance issues. By changing to a 10" rim I would assume it would only change the width of the tire at the rim, not at the tread of the tire.
This subject comes up every week but let's go over it again. On a 68-72 Chevelle/El Camino,you need at least 5.5" backspacing to run a 10" rim,,,not 5",not 5.25",,5.5" is the minimum. Now,I know Joe Blow is now going to say "I'm running a 15x10 rim w/295 tire w/5" backspace w/o problems". All I can say to those guys is Good Luck. You own a rare 68-72. However,for the rest of us bums :D ,we still need 5.5" backspace for that particular combo.
Next part of the question is a 50 series tire necessary? No,it's not any wider or narrower,,all the profile or aspect ratio tells you is the diameter i.e: all else being equal,a 50 series tire is shorter than a 60 or 70 series.
Normally a wider rim increases the section width (sidewall to sidewall width). It will normally not increase the tread width unless the rim width was too narrow to start with.

Last but not least,all this has been covered many times and can be found by doing a search. Trust me,it is not rocket science,guys.

I think we realize it isn't rocket science. The problem is everyone has an opinion. Not only everyone on this website but wheel & tire dealers as well. I want facts not opinions. I appreciate your help! 15 X 10 with a 5 1/2" backspace is what I will buy.
Now, one more question. I'm running 245/60 tires on the front. Should I stay with a 7" rim or go up to an 8" rim and what backspace if I go with an 8". Also, who has the best prices on rims?

Most tire dealers don't have a clue what really will fit one of these cars. That's why this site is so important,as you know. Some of us have been building these things over thirty years so we've kinda got a mental database what will fit and what won't. Sorry if my post came across wrong because I want to help you guys.

If it were my car,I would run an 8" rim with a 245 tire. Backspace could be from 4.5" to 5".

Thanks for your help. I don't know what I'd do without this website!