Gauge Calibration - Correction

OUMike · May 12, 2004

Hey all, I'm gettin' ready to buy a set of Tahoe Limited 16' wheels and was thinking of going with a 255/70-16 tire. I have a 94' Silverado 4.3L so right now I currently run on 235-45-15s. I think my current error is about +4 mph. How much of a difference should I see with the taller tire, and how would I go about correcting it? Is the error worth messing with?

What are opinions about tires? Anyone have any suggestions as to which tires are best bang for buck? I've been lookin' at Pirelli Scorpians, but not really sure what I want. Any help is appriciated.

hcvone · May 12, 2004

Your tires now are aprox 23.32" high, the tires you're thinking of getting are 30.05" or a difference of 22.4%, if your speedo reads 60 mph now it will read 46.5 with the new tires You can get new speedo gears or have the computer reprogrammed (not sure on the 94' ) The tires you get depends on where you live and drive your truck, I have been very please with the Bridgestone Revo tires

carguru · May 12, 2004

Are you sure that the stock tire size is not 235-75-15? Will make a huge difference in the calculation. A 45 series will have a little more than half the sidewall height of the 75 series. If it is a 75 series, that puts the overall diameter at 28.88 inches compared to the 30.05 inch overall diameter of the tire you are wanting to use. Your speedometer would read 3.9% slower than you are actually going. As said in the previous post, you will have to replace the speedo gear. Can't reprogram a '94. Hope that helps.

OUMike · May 12, 2004

yea, your right it is 235-75-15. So what does that mean? My stock tires are taller or wider than the new ones (255-70-16) or what?

Chris97K1500 · May 13, 2004

Your stock tires are 3/4" (9.25" wide) narrower and about 1.25" (28.8" tall) shorter compared to the tires you are wanting. So your new ones are going to 10" wide and 30.05" tall as posted earlier. So you'll be going faster than the speedo is actually showing you. Chris