Tire size

1997 CHEVROLET SUBURBAN
298,000 MILES • V8 • 2WD • AUTOMATIC
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JCOX
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I have a '97 Chev. Suburban 1500 with 298,000 miles. I recently purchased a portable GPS. However, it's showing a much slower speed than my speedometer. I checked my tires and find instead of 15" radius, I actually have 13.5 radius. How does that affect my speed, mpg, and miles logged on the odometer?
Feb 27, 2011 at 1:32 PM
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WRENCHTECH
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Your vehicle's speedometer reading is directly influenced by the tire dimensions (overall height). If your tires have that much lower profile, then you need to get that corrected as it's influencing many other things in the vehicle. The vehicles computer can be programmed for speedometer correction but getting the right size tires is what should be done.
Feb 27, 2011 at 3:41 PM