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1970 Mercury Cougar sat for 12 years

5K views 6 replies 4 participants last post by  1969XR7Vert 
#1 · (Edited)
1970 Mercury Cougar rear wheels

Does anyone know what size wheel is the largest that fits on the rear?
 
#2 ·
I'm about to buy a set of size 18in wheels. I had them test fit on a mock up car because I was skeptical. I'm getting 18x8.5 all around, but based on the test fit I would feel comfortable with a size 18x9.5 in the rear. Because I want to be able to rotate my tires I'm keeping the same size on all four.
 
#3 ·
I have 285/40-17's on 17 x 9 rims with 5.25" backspacing (important!) and they fit perfectly. I did a lot of measuring and calculating to come up with the largest I could run without problems.
 
#4 ·
Did you turn lock to lock with the mock up Max? 9.5 sounds pretty wide..!? Let us know what your backspace ends up being front and rear too......what are you going with? Of Course pics are a must! Nothing spruces up the old cat like new jewelry ;>P
 
#5 · (Edited)
Yes Bad69, I turned the wheels lock to lock. The back space on the rims is 4.5in with a -6 offset. I say I'm comfortable with the rears being 18x9.5 inches because there was a 69 Mustang that had them on the rear and it looked mean. But like I said, I need to be able to rotate my tires due to my propensity for marking white concrete with parallel black lines, so I'm sticking with the same size all around. I'll post pictures when I get back to KS, my wife is requiring that I allow her to buy them for me for our 25th anniversary in May. I'm still trying to decide what brand and size of tires I want or if I should get a set that puts out colored smoke (red or yellow) when you do burnouts.
 
#6 ·
Now that's my kind of wife! Happy 25th......I'd go red smoke - it's all the rage! ;>P
 
#7 · (Edited)
Max,

I hate to say this, but I'd be worried about 18" x 9.5" rims with 4.5" BS and a -6 (mm?) offset. Adjusting from my numbers (for 17" x 9") with a backspacing of 5.25", 9.5" would want to be 5.5" backspacing. The negative 6 (mm?) subtracts from the backspacing and so you have a real backspacing of 4.5 - 6 (mm?, if yes, that's 0.236") netting 4.264" BS. That puts the wheel/tire a full 1.24" more out of the wheel well than what I am running. If my numbers are correct that simply will not work on the rears.

From experience, I would say that if you feel you must have all four wheels/tires the same size, you are going to find that you are going to have to go with smaller rims and tires. The rims you specified might work on the front, but they are not going to work on the rear. Conversely, rims that would work on the rear (and are big) are not going to work on the front.

In short, if you want big tires and rims, you need different sizes front and rear, likely both rims and tires. This is what my experience has shown.

Regards,

Robert

P.S. Now what's this about tire smoke color? Is it a joke or a real thing?
 
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