Can I run 325/50/15?
 

I've asked this before and never got any real feedback, so i'll try asking again.

Has any one ran 325/50/15 on a 68-72 A-Body? If so, how much alterations where done and what was your back spacing?

I'm getting ready to install wheel wells so this would be the perfect time to do somthing. I don't want to cut the frame, just alter the wheel wells a bit. I'm running a 66 Chevelle rearend thats a 1/2" narrower on each side, that will give me a little more room.

Any feedback would be great, thanks guys.

I have 345/35X18's on my 70 GTO. It took a mini-tub and frame modifications to make them fit correctly inside the wheelwell. The only way you get 325's on the car (without the minitub/frame work) is to stick them outside of the stock wells. I never cared for that 'look' myself, but lots of guys do it.

If you do a search in the archives you will find a thread on this,dutch injun is running those tires with stock inner wheel wells.Im pretty sure I remember him saying he cut the outer wheelwell lips out and was running 15x10 wheels wirh 5.5 back spacing and 1/2 inch spacers?,anyway it looks great and he said hes had no issues.I run 295 65 15s on my 69 lemans (avatar) and it sits pretty low in the rear with modified springs and works great.Im running 15x8 rims with 4.5 backspacing and removed the outer wheel well lip as well as did a little finessing to the inner wheelwells with a big hammer lol,looks killer and hooks great.

Yes I am running them, I just switched to a 9" A-body rear, and they fit perfectly. I do not use a spacer(did need them with the taller 295 65 15 MT's), but I hammered the inner wheeltub, and have no wheelmoldings.

Found a couple pics,1. is dutch injuns gto with 325 50 15s and 10in. rims 2.is my 69 lemans with 295 65 15s and 8in. rims

I am also using the narrower early chevelle 12 bolt rearend. I measured my car in the back and determined that a 4.75" backspacing would be perfect to center the rim in the wheelwells. I have now mounted the rims and the centering is perfect. That should make you able to mount the maximum tire width. This assumes that you do not want to hack your car. If you are willing to hack it, then the outer lip is easier to trim than the frame rail is to move, so you would want to move the tire more outboard by using less backspacing. Start with my 4.75 figure. Then subtract half of the amount of lip you remove from the backspacing. For example, if you trim a full inch from the outer wheel lip, your new optimum back spacing should be 4.75 - 0.5 = 4.25". If you want to get into moving the frame rail, I would suggest you get under there and do your own measurements to make sure that you get it right. My car is a 69 Custom S, which is the same A-Body chassis as the GTO, LeMans and Tempest. I am running 275/50-15 BFG T/A Radials with plenty of room (3/4") on both the inside and the outside. If you try to push the envelope and go wider, you may have to use poly control arm bushings to reduce the amount the differential shifts side to side during hard cornering. I believe that I could probably use 295/50-15s right now with stock bushings and not have rubbing problems, but I haven't actually tried it. One more thing - using a narrower rim, such as 8" instead of 10" will decrease the overall section width of the tire and make it more likely to fit without rubbing. My rims are 15X8s. Just consult the tire manufacturer for the recommended rim width for your choice of tire.

I am running a 295/50/15 now without any issues and have room for at least an 1" more back spacing. I know the wheel well will have to be worked. When we weld in the new wheel wells next weekend we are going to try to move it out a little, not enough to see, but hopefully enough to make a little difference. I'd keep running the 295/50/15 if there was a wide selection from tire companys, in fact it would be an open and closed case if they sold the BFG drag that size.

Thanks for the input everybody