I am looking at upsizing the tires on the burb, the overall diameter will be 1" bigger. Will I see any difference in the speedo or is this acceptable. Thanks.

 

If your stock tire diameter is 30.6 " like mine then you will see about a 3.3 % increase in speed. So at 60 mph you will actually be going 62 mph. That doesn't sound too out of line to me. if you know someone with a tuner they may be able to adjust for the tire size for you. You can probably get away with that tire size increase without any problem.

 

2 weeks ago they did one of those speeed signs on my street, going from 245/75's to 285/75's i saw no difference in speed.

 

I had 265/75-16s stock, went to 285/75-16, seemed pretty straight on by the speed signs. When I had my pcmforless tune done I had them program fro 285's, now I'm really going something like 4 mph slower than my speedo reads....last speed sign said 74 when my speedo said 78-79. You should be fine without a tune.