hi i just put bigger tires on my truck just the back for now i had 235/7015 i went to the irocz rim and put 255/7016 on and noticed my speedo is off now 4-5 mph how do i fix that please help i am putting on an add a leaf this week and i ordered a pa-152 2in bl so i put bigger tires on hope someone can help

 

OK, so what did you do to your truck? your post was all one sentence and isn't the easiest thing to read. I got the part that you put the older iroc wheels on the truck and that your speedometer is off by 4-5 mph.. after that it kind of runs together and you lose me

 

i put the 16in irocz rims on now my speedo is 4-5 mph off and it doesn't shift right anymore

 

The dealership can reprogram you ecm for the new tire size. Luckily, we have a Tech2 at school, so I did it myself when I switched from stock tires to 255/60/15's