speedometer change with bigger tire?

I am going to change my tires from a 265/70/16 to a 285/70/17 and i was wondering how much my speedometer is going to change and if it is worth getting re-calibrated
thanks

 

not sure how much, i did the same thing and really did not notice much when i drive by the signs that say your speed, not worth recalibrating.

 

ok thanks for your help guys

 

I asked the dealer about having the speedo re-calibrated. They said there is no such adjustment, however there are devices that claim to do it. The ones I've seen are kind of pricey for the speedo being off by only 3-5 mph at 60. I wouldn't spend my money on one.

 

If your truck is like mine, your already going slower than the speed on the gauge is showing.

I recently went on a road trip to pick up some goodies for my truck, and traveled a long distance on the PA Turnpike. They had the portable speed guns set up at a couple of places, and every one of those showed me going 2-3 MPG slower that the gauge was actually reading.

I now have 265/70R17's and my actual MPH is right on what the gauge shows.

 

i have never had my truck clocked before but even if it is only 2-3 kms over that shouldnt be a big dealer like the others guys told me

 

but thanks i have never heard of that before