Company Representative of RPI Power
Join Date: Jan 2006
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Be sure to check out the revs per mile on TireRack's site. Though you should simply be able to multiply out the size to calculate speedo error, different manufacturers rate their tires a bit differently, and can even vary with different lines.
Continental Conti Sport Contact 2 285/35R19 tires are rated at 776 revs per mile on a measuring rim width of 10.0". On our stock 9.5" rim width, it's a bit taller, so you're below 776 revs per mile. I'm not sure how much lower, but it shouldn't be too much, probably 765 or so.
The front 255/35R19 are rated at 904 revs per mile on a 9.0" rim. Again, on our stock 8.5" wide rim, it's a bit taller.
Anyone know which end the speedo is attached to? Is it the rear?