Ummmmm, that calculator is not brand specific; and I believe from my past studies that the tire sizes as stated on the side of the tire are relative to the size of the tire - the 285 being the cross section width of the tire at its widest point (the sidewall) in millimeters. The 55 refers to the aspect ratio of the tire, or its sidewall height percentage of the cross section (55% of the 285 number). So there should not be a great variation in height, I wouldn't think. Of course, as you stated, the only real way to be sure would be to jack the car up off the tire and measure.
OK - just went to Yokohama's web site, they list inflated height at 30.4", and Bridgestone's web site says 29.7" for the H/T Dueler - still no guarantees without measuring, but interesting how they are both .1" larger than the calculator states. I guess another consideration would be tread wear - a new tire with 12/32nds of tread vs your worn out tires at 5/32nds, adds another 7/32nds of height to the equation in mileage comparisons before and after the tire switch. I'm done........
Oh, and Pete - sorry to hijack your thread and turn it into a discussion of tire dimensions!
Reply With Quote