Tires Size

[jaystone10]

I have bought new Tires went from 265-65-18 to 275-65-18 and now my speedometer is off. Can the Computer be reprogrammed to correct this or do I just live with it?

[Stex]

Yes on my 09, I did the same on tires, dealer told me no need to unless you go over 285s...check with them....mine is still on with 275s...not a big difference 265 to 275

[uh6tdrvr]

My gps barely shows 1 MPH difference with my 275 65's....and dont talk to that dealer....the speedo varies on Height not width!!!

[jaystone10]

If my GPS is correct mine is off about 1 mph when driven under 60 but when between 70 to 80 it's about 5 mph off

[Starrman]

the speedo varies on Height not width!!!

 

true but the 65 is the height of the sidewall as a percentage of the width, so 65% of 275mm is more than 65% of 265mm.

[txab]

If my GPS is correct mine is off about 1 mph when driven under 60 but when between 70 to 80 it's about 5 mph off

 

.5" difference in tire size. At 60 you should be off by 1 mph. At higher speed I would think maybe 2 mph off at the most. 5 seems too much. When I changed tire size by .5, mine was adjusted by about 2 mph. But doesn't matter. You can easily recalibrate the speedo. Or just use your GPS if you feel it's trustworthy.

[uh6tdrvr]

Trust the GPS before you trust the speedo

[Starrman]

Here's a good online tire size calculator that will compare different tire sizes, revolutions per mile, and give the difference in speed for each.

 

http://www.1010tires.com/TireSizeCalculato...p?action=submit

 

A handheld programmer like a Predator is capable of correcting for tire sizes also.

 

Going from a 265/65 to a 275/65 is only like a 1% difference in height and shouldn't effect the speedo hardly at all. You should only really need to worry if the difference is 3% or more.