I have 255 70 17 and want to install 285/70/17 on my stock 2005 screw 4x4 with stock rims. Is it mandatory to recalibrate speedo or can I just live with it
What will be the effects to the truck and the sppedo??

 

i would think it would only be a few miles an hour off. even with my xcal2 mine is 2 miles an hour off with the 33's. i need to play with the numbers a little more and see if i can nail it down.

 

No, you don't have to recalibrate but it would be a good idea simply because your speedometer and odometer will be off. I went from 30's to 33's also and my speedometer was off 5 mph at 60 mph.

 

Wandell, I went from stock 18s.... I think 275's to 325/60/18. Do you have any idea what affect that had on my speedo? I just had it done yesterday and havent had time to actually mess with it.

Also, do you have a suggest for calibrating it and how much it might cost? I dont have an edge.....

 

Look at the tire manufacturers website for the exact height of those two tires. I think the 325's are about one inch taller than the OEM tires. Your speedo is probably only off one or two miles per hour. My dealer told me they could recalibrate for about $100, but I decided to go ahead and spend $300 on a Superchips tuner and do it myself and gain a little performance.

 

I tried to send you a pm... but cant yet. I just wanted to say thank you.