When mounted as duals the tire capacity is reduced due to the fact that tire loading is not equal so there needs to be some room for error. In addition most roads are crowned increasing the load on the inside tires. From RV experience the inside tires wear the most and are usually the first to fail. When one fails that load goes onto the remaining tire. Often a tire failure will go unnoticed until the 2nd one fails. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Dave Mcneely
Sent: Wednesday, June 11, 2014 2:46 PM
To: vanagon@GERRY.VANAGON.COM
Subject: maximum tire load question

I am getting information together for selecting new tires for my Volkswagen Vanagon GL Campmobile, 2.1 waterboxer, manual transmission.  It is tan, Scott.

I am not intending to start a tire thread.  I have a single question.  In reviewing load data for several different tires, I see two different values given for the same tire.   The maximum load may be given as Load Range 106/104 followed by something like S65 psi 2094 lbs and D65psi 1994 lbs.

What do the S and D terms mean (I know psi of course) and why the two different load index values and two different maximum loads given for the same tire?  I reviewed tire specification descriptions on TireRack.com and on USDOT web pages and found descriptions of load index and maximum load, but nothing about the S and D or different loads for the same tire.

David McNeely