Throwing off ODO

[SUODRAXAH]

I'm looking at getting new tires and I was thinking about getting 40r18's. This will make my speedo off by .1mph... Does that mean that every 10miles my ODO will be off 1 mile?

 

[Stevenredx]

What width tire??? 255?

???/40/18

 

[x-runner kid]

yes if it truely off by .1mph but you can have it recalibrated to that tire size you can program it yourself using a programer or you can have someone else do it but idk where you would go I would guess a tire shop might be able to or the dealer would be my bet

 

[SUODRAXAH]

What width tire??? 255?

???/40/18

yeah 255s. I didn't think that mattered as far as throwing off the odo/speedo, does it?

 

[Stevenredx]

yeah 255s. I didn't think that mattered as far as throwing off the odo/speedo, does it?

Yeap, sure does :top:

test out some different sizes here :top:

http://www.1010tires.com/TireSizeCalculator.asp

 

[CBRBob]

.1mph or .1%? If it is .1mph, then at what speed, because the faster you go, the more the worse it will be. If it's .1%, thats essentially NOTHING. At 100mph it would show 100.1mph, 50mph would show 50.05mph. 1% would be 101mph or 50.5mph.

Now going from a 45 series to a 40 will not only make the tire look 'lost' in the wheelwells, it will be off by more than .1mph(or whatever). It looks like it will be off by a full 3%. So at 65 it will show 67mph (103mph and 51.5mph).

 

[BSP06XRU]

yeah 255s. I didn't think that mattered as far as throwing off the odo/speedo, does it?

The first number is the overall width of the tread.
The second number is the percentage of the width for the sidewall height.
The last number is the rim diameter.