60 vs 70?

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jscott

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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.










  • Current Tire Size: /  R 






New Tire Size: /  R 
 




Side by side Overlay
255x60xR15-255x70xR15_sbs.png



 




 


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%




 

jscott

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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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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.

 
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Lazarus

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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. 

 

Don C

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jscott

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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.

 

jscott

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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.

 

droptop73

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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. 

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