post #1 of Old 10-15-2004, 01:57 PM Thread Starter
SureThing
Registered User
 
Join Date: Oct 2004
Location: Upstate SC
Posts: 46
Metric vs. Standard tire sizes

Some where I read a 265-75-15 is about the same thing as a 31x10.5x15. What is the metric size for a 30x9.5x15?

Also, in general, how do you figure it out?

SureThing is offline  
post #2 of Old 10-15-2004, 02:12 PM
BigWaylon
tubework is cool...
 
BigWaylon's Avatar
 
Join Date: Nov 2003
Location: Charlotte, NC
Posts: 7,381
there are several websites that will convert for you...but, there's obviously math behind the whole thing...

you need to know two things:

1. what the "measurements" on the tires are
2. there are approximately 25.4 millimeters in an inch

knowing those two things, you can go from standard to metric and back...

31x10.50x15
31 = tire height in inches
10.50 = tread width in inches
15 = rim size in inches

265/75/R15
265 = tread width in millimeters
75 = profile ratio (width divided by the sidewall height)
15 = rim size in inches

to get the metric size for a 31x10.50x15:

10.50*25.4 = 266.7 (your new width in millimeters)
31 (height) - 15 (rim opening) divided by 2 = 8 (16/2) (which is your sidewall height)
8/10.50 = .76 (new sidewall ratio is 76)
so, your 31x10.50x15 is actually a 267/76/R15, which is very close to your other tire


to get the standard size for a 265/75/R15:

265/25.4 = 10.43 (your new width in inches)
265*.75 = 198.75 (sidewall height)
198.75*2/25.4 + 15 = 30.65 (your new height in inches...take the sidewall, multiply by 2 to account for top and bottom, divide to get number in inches, and add rim opening in inches)
so, your 265/75/R15 is actually a 30.7x10.43x15...also very close to your other tire...

hope that helps...

Greg

2001 TJ 60th Anniversary Edition (details in Profile)
www.carolinarockshop.com
All the pics I have...including a Table of Contents
BigWaylon is offline  
post #3 of Old 10-15-2004, 02:53 PM Thread Starter
SureThing
Registered User
 
Join Date: Oct 2004
Location: Upstate SC
Posts: 46
SureThing is offline  
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
What is the Standard to Metric Conversion of a 31x10.5r15? bensmiata Tires & Wheels 8 01-15-2010 10:19 PM
Standard VS Metric Tires (305-70-16 VS 33X12.5X15) Xiled1 Tires & Wheels 13 01-23-2009 09:07 PM
Metric conversion for tire sizes Duck Dodgers Tires & Wheels 5 12-30-2007 09:50 AM
Metric to standard tires size chart renegadeyj Tires & Wheels 3 11-25-2005 08:05 AM
Help with USA tire sizes in metric. Popol Tires & Wheels 10 12-09-2003 09:45 PM

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome