Is there a reference to find actual tire size versus stated size? - JeepForum.com

 
LinkBack Thread Tools
post #1 of 9 Old 03-10-2014, 01:09 AM Thread Starter
73azbronco
Registered User
2013 JK Wrangler 
 
Join Date: Mar 2012
Location: scottsdale
Posts: 650
Is there a reference to find actual tire size versus stated size?

Any reference out there to find true tire sizes versus stated for the different brands of 33 or 35's?

Example, I have Toyo open country, they are stated at 35 inches, but measure a surprising 33.75 inflated to 30psi. Until I measured them, I would have sworn they were easily 35.

73azbronco is offline  
Sponsored Links
Advertisement
 
post #2 of 9 Old 03-10-2014, 03:12 AM
JeepWranglerNation
Member
 
Join Date: Jun 2009
Posts: 374
Post Delete
JeepWranglerNation is offline  
post #3 of 9 Old 03-10-2014, 10:57 AM
CJ7nvrstk
Registered User
1985 CJ7 
 
Join Date: May 2011
Location: Prosper
Posts: 1,229
Quote:
Originally Posted by 73azbronco View Post
Any reference out there to find true tire sizes versus stated for the different brands of 33 or 35's?

Example, I have Toyo open country, they are stated at 35 inches, but measure a surprising 33.75 inflated to 30psi. Until I measured them, I would have sworn they were easily 35.
No.

RED Friday. Remember Everyone Deployed
45 MB, 67 Commando, 85 CJ, 08 JKU, 11 JKU
CJ7nvrstk is offline  
post #4 of 9 Old 03-10-2014, 11:08 AM
mike_dippert
hodophobic
 
mike_dippert's Avatar
2005 LJ Wrangler 
 
Join Date: Jan 2006
Posts: 3,501
Garage
Actual size will vary depending on inflation, load, and wheel width. Easiest thing is to not worry about it. Second easiest thing is to find someone with a similar vehicle and the tires in question that has measured the actual size.
mike_dippert is offline  
post #5 of 9 Old 03-10-2014, 11:10 AM
WXman
Registered User
2001 WJ 
 
Join Date: Jun 2003
Posts: 3,517
Rule of thumb I always use is take the listed diameter and subtract 1 inch. This usually works out great for tires under 35".

Remember, the manufacturer measures tires with the bulge of the sidewalls while mounted on a specific wheel included. You and I measure without the sidewall bulge. That's where the inch gets lost.

'92 YJ - heavily modded
'96 ZJ - heavily modded
'05 KJ CRD Limited - 370 lb./ft. from a 4-cylinder and trail ready. Pure awesomeness.
'11 Mango Tango JKU Sport - Mods
'12 Dozer JKU Sport S - 6-speed - ACE rock rails - Max Tow package - Daystar spacers - 33x12.50 Duratracs
WXman is offline  
post #6 of 9 Old 03-10-2014, 04:45 PM
Charley3
Web Wheeler
1999 XJ Cherokee 
 
Join Date: Mar 2013
Posts: 5,538
Look at tire height in mamufactirer's specifications. That's the height of tire when inflated to max psi.

But you won't be using max psi. So it will have less tire height.

Also perhaps what Wxmam said too.

Warning: I often edit my posts a few times to get them complete, or to correct errors.
Charley3 is offline  
post #7 of 9 Old 03-11-2014, 06:05 PM
Scrmngchicken
Registered User
2001 WJ 
 
Join Date: Mar 2014
Location: Louisburg
Posts: 168
Tire sizes are based on an inflated tire that is unloaded. Meaning not on a vehicle.

So no, there is no standardizing. Especially when dealing with different manufacturers. And when you factor in quality differences, it further complicates things.

Think of sizes as a guesstimate.
Scrmngchicken is offline  
post #8 of 9 Old 03-12-2014, 10:54 AM
Ferrachi
Registered User
2003 TJ Wrangler 
 
Join Date: Jan 2012
Posts: 445
I wasn't happy that a set of Duratracs I bought (31") measured out just a tad over 29". Wasn't what I expected at all and realized I had some researching to do. Use google, many other posts on this forum and others which talk about this.

http://www.jeepforum.com/forum/f96/a...specs-1206007/
Ferrachi is offline  
post #9 of 9 Old 03-12-2014, 06:15 PM
mike_dippert
hodophobic
 
mike_dippert's Avatar
2005 LJ Wrangler 
 
Join Date: Jan 2006
Posts: 3,501
Garage
Quote:
Originally Posted by 73azbronco View Post
Any reference out there to find true tire sizes versus stated for the different brands of 33 or 35's?

Example, I have Toyo open country, they are stated at 35 inches, but measure a surprising 33.75 inflated to 30psi. Until I measured them, I would have sworn they were easily 35.
FOUND THE ANSWER!!!!
Look at the mfg's stated revs per mile.
20,168 / [insert rev's here] = more realistic actual size.
For example, your tires (MT's?) have 596 rev's per mile, which equals 33.8". Much closer than the 34.8" inflated diameter spec.

Quote:
Originally Posted by Ferrachi View Post
I wasn't happy that a set of Duratracs I bought (31") measured out just a tad over 29". Wasn't what I expected at all and realized I had some researching to do. Use google, many other posts on this forum and others which talk about this.

http://www.jeepforum.com/forum/f96/a...specs-1206007/
and yours are 681 revs, which is 29.6"


A 35" circle has 576 rev's per mile.
A 33" circle has 611 rev's per mile.
A 31" circle has 650 rev's per mile.

I've found that most 35" tires are in the 595-605 range.
33's are mostly in the 630's.
I'm not sure about 31's.

I haven't looked into it, but I believe the discrepancy comes from load bearing. The inflated diameter spec is the tire inflated to maximum psi, with no load. Revolutions per mile is probably the tire at it's maximum psi and load, meaning the tire has it's flat spot at the contact patch resulting in a shorter radius to the ground (which is half the functional diameter of your tire).
Hope this helps someone.
mike_dippert is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




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



Posting Rules  
You may post new threads
You may 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