275-60's or 275 50's

I have narrowed down my rear tire selection to either 275-60's or 275-50's. Does anyone recommend one over the other? I have 3.08's so the 50 series would help a little with the gear ratio. But would it look good on the car? I am putting them on factory 15x7's. Also i plan to run 235-60's in front. I have a 1.25 inch sway bar so tire contact could be an issue. The 225-70 14's I have now look like they rub on hard lock turns. Thanks for any input. Other ideas are appreciated! Brian

 

Brian, the 60's will give you:

- higher cruising speed for a given rpm
- better traction for acceleration (larger contact patch and less shock to the launch pad)

The 50's will give you:

- better handling, less sidwall flex
- somewhat lower gear for acceleration.

I have BFG T/A's 255/60R-15's on 15 x 9's, and they fill the quarter's nicely. They are 25 7/8" in diameter. I recommend widening the rims in the rear to 9" or 9 1/2". With the proper backspacing you should have no problems.

The 235/60R-15 will work nicely in the front with 15 x 7's. Keep in mind you will have a little different rake to the body with 50's vs. 60's in the rear.

 

Thanks for the reply,Craig. I thought I had read that some people were runnung 275 60's on the 15 x7 rims. I sthis going to be a problem? Brian

 

Brian I would go with 255/60 with 15 x 7 rims, like Larry did. Don't get me wrong 275's will fit but the tires will balloon out from the rim and look too wide and be less stable in the curves. If you want less gear for the highway this is one way to do it however.

Check your backspacing (I can't remember what stock is) I'm guessing it should be at least 4 or 4 1/2 inches so the wider 275 tire won't rub the quarter panel lip. Someone may have more input on this?

I was implying above you could go as wide as 9 or 9 1/2 inches wide with no interfearance problems...with proper backspacing. I think 5 inches of backspacing is about the max. you could go, I have 4 1/2 backspacing and there is plenty of rim clearance (~1") on the inboard side. Good luck.

 

I currently have 3.08's so I really want more gear not less. I may go with the 255's instead. Eventually I plan on installing 3.55's. Brian

 

I use 275/60's on the rear and 225/70's on the front with standard 15x7 rallyes for that classic big n little look and the larger tires really fill out the wheel wells good.

The 7 inch wheel is really a little narrow for the rear tires so the center of the tires wear noticeably more when doing the old smokie deal.

I and a couple of buddies are going to buy some of the reproduction 15x8's and use them on the rear for that reason.

My car is 72 skylark/gs clone and the rear tires dont have alot of clearance but they dont rub.

One thing to think about when running tires of different sizes is your spare. Especially if you're car has a posi rearend. Heaven forbid you'd get a flat and have to use that bumper jack on those $400 rechromed bumpers. But if you did you should not ever drive more than a block or two with mismatched rear tires.

For that reason I have a 235/70 for a spare. It will still fit on the front and is within a .10 of the 275/60 new diameter. They are substantially worn shorter now I'm sure. :TU:

 

:Smarty: I have 275-60 15's on the back and 235-60-15's up front. Im very satisfied with the look, but 1 prob the 275's feel a little mushy around the turns on 15 x 7 rims. I have the same 275's on a 15 x 8 ws6 rim on my T/A and they feel totally solid. Just my .02 try 255's even though there a bit less wider it will feel more solid around the turns. If cornering is not a big concern the go with the 275's

larry

 

I will go to 15x8 rears eventually because the chrome on my rims isn't the greatest anyway. But I do have the 275's in back now and they really look good! A big diff from the 14x6 225/70's that were there. Now if I can only sell the 14x6's! Brian :Brow: :Brow: