What will happen if i use 235.55.17 instead of 235.65.17?

[bwilliams]

I have an 2002 X5 3.0. It came with 235.65.17s on the star wheels. I was given a new set of 235.55.17 will I screw up the computer by using this size?

[E5M1R]

245/55/17 is the smalest 55/17 tire that you can use, difference is 4,9% in size, maximum diference can be +-5%
Your sugested 235/55/17 are 6,4% smaler, so a no go there.
Your DSC would not freak out, rather over react on slightest spin, your odometerwil mos likely show wrong speed.
There are other things that can be affected as well I would not recomend those tires

[bwilliams]

Thanks, will not use then.

[MrLabGuy]

Here is how the the numbers work out for those who don't know.

Example above. 245/55/17

245 is the width of the tread.

Don't feel bad if you don't know this...Many tire shops don't know this as well as I've discovered.

55 is the percentage of the sidewall height as it relates to the width of the tread meaning 55% of 245 which represents how high of a profile the tire is in comparison to the width of the tire.

17 is the size of the rim.

[rayxi]

There are many tire size calculators on the Web. Here is one:
http://www.1010tires.com/TireSizeCalculator.asp