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Now that I have my two new Magnum 500 15 x 8 wheels I am ready for tires.  My plan is to go 255 x 60 15 but I have a question.  I see there is a 255 x 70 15 which is taller  .  Will these work, will these give my rear end (car) a little more height?  I am not a fan of the normal stance of sitting back in the rear just a bit.  Was going to try new lower coil springs up front some time in the future but wondering if the larger tire would help with that? Cannot imagine a clearance problem on the car and I know the speedo will need adjusting but my speed is pretty far out now so that has to be fixed either way.


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Side by side Overlay
255/60r15 vs 255/70r15 Tire Comparison Side By Side
  255/60-15 255/70-15 Difference
Diameter inches (mm) 27.05 (687) 29.06 (738) 2.01 (51) 7.4%
Width inches (mm) 10.04 (255) 10.04 (255) 0 (0) 0%
Circum. inches (mm) 84.97 (2158.27) 91.28 (2318.5) 6.31 (160.22) 7.4%
Sidewall Height inches (mm) 6.02 (153) 7.03 (178.5) 1 (25.5) 16.7%
Revolutions per mile (km) 745.66 (463.33) 694.13 (431.31) -51.53 (-32.02) -6.9%
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No one?  Guess the 70 are not something I should think about then if no one has used them????


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4 hours ago, jscott said:

No one?  Guess the 70 are not something I should think about then if no one has used them????


If this helps, I have an original, never-been-on-the- car E70-14 bias ply tire. It measures 26" diameter. This of course is a 14" rim, therefore I would think the same ratio tire on a 15" rim, would be 27" give or take. Personally, I would not go to the taller sidewall especially if it is 29" diameter. If you want the back end a little higher, NPD sell Eaton 1" longer shackles.

Edited by Stanglover


 I learn something new every day!

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I have a 235/55/R17 in the back, which is 27.2” in diameter. It is actually kind of big and fits the wheel opening very well. I can’t really imagine two more inches in diameter fitting or looking right, for what it’s worth. 

I have replaced my rear leaf springs with 4 1/2 leaf, standard-eye springs - which raise the rear about as high most would want - and I am not sure a 29” would work well even in that setup. 

I like a slight positive rake on a muscle car and, like you, don’t really prefer a negative rake on our models. But the 2” taller diameter tires only add an inch of height; I’d personally try changing leaf springs or adding a lift block to raise the rear. I am not really into lowered cars myself, but a lot of guys do like the shorter front coils. 




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The /70 will raise the rear of your car about 1-1/2" over the stock size of about 26.1". Of course how much it will raise it compared to the front is the size of the front tire.

You'll also have to correct the speedometer with a different driven gear.

Tire Sizes - Suspension, Handling, Brakes, Wheels and Tires - 7173Mustangs.com

Speedometer Gears - Engine, Transmission, Drive Line, Etc - 7173Mustangs.com



“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein


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Now on the horns a of a dilemma .  I settled on 255 x 60 R15...........was just about to order them on line but decieded to make sure the new magnum 500 wheels I just bought fit correctly.  The box showed the right size but hands on never hurt.  They fit fine BUT as I was putting back the tire on my car i noticed they are currently 215 x 70 R15!!!   I am not sure why I thought they were R60s??    A shop I first brought the car into to have some work done put them on with the new 7" magnum 500's.  The tires were at the shop and I traded some parts for them so they were pretty much free.  Soooooooo, I measured and the 255 x 70 would indeed be 2.2 inches higher then now and that is too much I think with a wider tire.  The 255 x 60 R15 is pretty much the same height as the 215 x 70 R15 that are on the car now, so that would be a wash, it would remain the same height.  But if I put new rubber on all 4 corners then perhaps I can lower the front.  225 x 60 on the front would be 1.22 inches lower then they are now.   More research needed.

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research done, going to go with 255 x 60 15 in the rear and 235/60 15 up front.  That should be about 3/4" lower in the front then what I have now so it is a start.

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I just saw this post. I ran 255/70/15 on the back of mine years ago. They fit fine on a 15x8 Magnum. I added 2" lowering blocks and offst the pins to move the tire into the center of the wheelwell just for looks but not necessary. 



[align=left]Jeff T.


When I die I want to die like grandpa, peacefully in my sleep... not screaming, like his passengers. [/align]

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