hey guys. i have some questions about going from a 245/75 tire to a 285/75:

1. currently, for example, my truck shifts gears at 45 and 55mph. if i'd go with 285s, to my understanding i'll be going 5mph over what my speedo says. will the truck shift when it actually reaches 45/55mph (for example) or will it be out of whack and shift when it is actually 50/60mph? (i'll reword this if y'all dont understand.)

2. Odometer- as in the last question, i'll be going faster than with the smaller tires. will i have to do something with my odometer to account for this?


thanks in advance!!

 

yes the odometer will be thrown off with the increase in tire size but i dunno how the shifting will be affected id say itll be different everytime depending on the rpms ur turning an u can buy a recalabrating? kit an u should be good to go

 

under normal throttle conditions, vehicle speed is a controlling factor in the shift points.

i'd find some kind of programmer or tool that will allow you to change tire sizes in the computer. i recommend edge or gryphon.

 

Can a dealership or mechanic shop do this?

 

Why not go with a 285x65 tire and not have any noticable difference (other than having the wider tread width). The lower profile tire will be within 1/10 th. inch of the same diameter as the 245x75 tire.

 

From my experience with my old ranger when i went from stock to a 33 inch tire my speedometer was slower than my actual speed. So when i was going 70 my speedo read 50

now with my f150 i have 315/75/16 tires and its geared but my speedo reads 10 mph faster than actual speed. So when i was going 70 my speedo read 80