2004 chev tires

The only thing you are changing acording to what you have in your post is the width of the tires the tire height 75 and the rim size 16 are staying the same so your spedo should not change at all

the number 75 is the height of the sidewall as a percentage of the section (NOT tread) width. a 265-75R16 is indeed taller (75% of 265mm vs 75% of 245mm) than a 245-75R16. when I swapped out my worn out Uniroyal LTL's in 245 for BFG AT K/O's in 265 I noticed that my speedometer is now 5% off (1 MPH per 20 MPH speed).

-Bret

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I went from 245-75R16 Firestone stock tires to 265-75R16 BFG KO's and had the dealer reprogram for the new tires to correct the speedo. They warned that you might have ABS issues as well if you don't reprogram. I think it was $30 to do the programming. BTW, my truck is a 2000 Silverado, but should be the same for all newer ones...

-Jeff

Bret is correct. You will gain 1 to1.5 in. in height when you change tire sizes from 245 to 265. I had a GM dealer adjust my computer to correct the speedo when I changed my tire size. They told me it could be changed providing I used a tire size that is available on GM trucks when new. The Z71 trucks have 265 tires when new so it was not a problem.