Need help calculating tire diameter

[dober250R]

How do you figure out the tire diameter of a tire? My truck tires a 265/70's........... I need to re-calibrate my speedometer with my new programmer I just bought, but I need the diameter. Thanks.

[honduh440]

http://www.sstire.com/tireheights.html

[dober250R]

thanks honda.........Sometimes it's easier to post in the open forum than to search through a search engine:p

[underpowered]

Breakdown of metric tires.

265/75-16 (just as an example)

265-- this is the section width. supposed to be the widest part of the tire, not the tread width usually.

75--Aspect ratio. this is a percentage of the section width. this is the sidewall heigth. so on this tire the sidewall is 75% of 265mm, or 198.75mm

16--Simply the wheel diameter.