[BigRedChevy]

Got a new to me 06 CC LBZ trying to get my brain wrapped around this diesel truck world. It already had on it 285/75 tires. Does over size tires void warranty? How can you tell if the torsion bars have been altered in anyway? At 70MPH on the speedo my GPS says I'm doing 73MPH ~ 4% Why/How do the oversize tire alledgedly hurt fuel mileage looks like the worst it would do is be miscalculated by the computer by 4%
thanks for any info.

Most people fix the speedo and odometer with a programer so they are useing the correct mileage.