okok, i'm sorry for using the "S" word, can somebody pass along the equation so us non-metric guys can figure out what the size is?

I'm sick of not knowing how tall some of these tires are!

Stupid Me, known as...
Scottie B

 

http://www.tirerack.com/tires/tiretech/general/size.jsp

 

First # is width. divide that number by 25.4.
The second number is the ratio of side wall for example
if i'm running a 315/70R16 tire
315/2.54 =i have a tire that is 12.4" wide
Then 12.4*.70=8.68 inches of sidewall
so 8.68+8.68+16=33.36" tall tire.
Hope this helps.

 

Just as a note to help from throwing people off the .75 should be .70 given the tire size you listed. That 2nd number is called the aspect ratio and is simply the sidewall height expressed as a percentage of the section width.

 

GO to google and type in "metric tire converter" the first site should be a metric calculater, add that to your favorties and there you go.

 

thanks for the help!!


...metric still sucks!

 

oops it has been corrected... damn brain farts!!!

 

Well actually the 9.3 should be changed to 8.68 and the 34.6 should be changed to 33.36. But whos counting.


Actually it would have been easier to change it to a 315/75/16 as all the math would have been correct then. Anyways, people should get the drift anyhow.


Oh, also get used to metric, its going to be here to stay. Most of the parts on new trucks are metric and most ag equipment is now metric. If you look on John Deere planters and Case combines ~70-80% is metric.

 

Very usefull information! Since you guys are so fluent in the tire language, maybe you could help me out. I've got four tires measuring 265/70/17. Using your formula, I have a tire height of 31.6. I have a spare on a 16' rim. What size tire can I put on the 16 to match up ? If I use a 275/70/16, I come up with 31.16. If I use 275/75/16, I get 32.24. Am I correct in assuming that the smaller one will be better due to tire wear? Should I just get another 17" rim and match the set? Any suggestions are appreciated.

 

A 265/75/16 will be within a fraction of an inch of being the same diameter

 

Yes, a 265/75/16 is the same diameter as a 265/70/17. By keeping the section width the same, but by decreasing the aspect ratio one unit (typically goes in 5s) and increasing the rim dia. by 1" you get essentially the same size tire overall with shorter sidewalls.

For example:
265/75/16 = 265/70/17 = 265/65/18
285/75/16 = 285/70/17 = 265/65/18
etc

 

!@#$%*&$#@ Note to self must be more meticulous in posting correct and accurate information!!! !@#$#$*&