Tire size

76_Cobraii_mustang

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So I have a 76 cobra ii. It has a 9 inch in it and 60's leaf springs. I am going to be putting 2 more leafs on each side to give it a rake. I have 15 x 8.5 center line rear rims. What is the biggest tires I can run? Stock wheel wells.
 
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MustangIIMatt

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76_Cobraii_mustang

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Thanks.
I am look for the back rims still. Should I get 15x7? Are the 15x8.5s to big?
 

LILCBRA

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I have 15x8, 4-1/2 back space and run 265/50-15s. I'm pretty sure I had to massage a couple locations in the wheel well like the area where the seat belt retractor sits. If I hit a good bump and bounce just right the outer lip will rub on the sidewall for a split second, but that's usually only if I had a passenger in the back seat. If you rolled the lip and went with a little shallower back space you might be able to run something a little larger which I think has been done. You'd have to go through the link that Matt posted, I believe what I'm remembering is in there somewhere as well as different pics of my car when I was fitting these wheels and tires that kinda shows some of the clearances on a semi-stock rearend setup.
 

76_Cobraii_mustang

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Jul 23, 2018
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I have 15x8, 4-1/2 back space and run 265/50-15s. I'm pretty sure I had to massage a couple locations in the wheel well like the area where the seat belt retractor sits. If I hit a good bump and bounce just right the outer lip will rub on the sidewall for a split second, but that's usually only if I had a passenger in the back seat. If you rolled the lip and went with a little shallower back space you might be able to run something a little larger which I think has been done. You'd have to go through the link that Matt posted, I believe what I'm remembering is in there somewhere as well as different pics of my car when I was fitting these wheels and tires that kinda shows some of the clearances on a semi-stock rearend setup.
I read your post. You have 15x8 and they look nice but I think it will make my car handle crappy because I have the 15x3.5s for the front. I think I will go with the 15x7's
Know anybody that has 15X7 centerline autodrags 4x4.5?
 

LILCBRA

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Having 15x3.5 wheels on the front with anything much bigger than a 15x6 wheel will most likely give it lopsided grip and it won't handle all that great to begin with. The 3.5 wheel is more or less so people can specifically run bigs and smalls which isn't a handling thing, it's mostly for straight-line grip for drag strips. So a 15x7 or a 15x8 really isn't going to matter, it'll all be the same in the scheme of things.

Now if you're looking to use the 15x7 in place of the 15x3.5 on the front, that's a different story altogether. I guess I'm under the impression that you're asking about rear fitment. I don't really have any experience with a wheel/tire on the front that's much wider than a stock width. I do know that your overall diameter will be limited, and I do know that if your backspacing isn't right the wheel will run into the upper control arm, but I don't know if there's a 7 inch wide wheel that works without rubbing the control arm AND doesn't stick out so far that the tires have clearance issues with the fender. If you can't find anyone who has anything like you're looking to do in the wheel and tire thread, you might need to pick up one of the tire tools from Summit or Jeg's or something.

 
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