The tires on my motorhome are stamped 16PR, Load range H, load index 145 single/143 dual. 6940 Single/6345 dual pounds capacity @130 PSI. As for front rear I am running Continental HSR (Heavy Steer Radial) front and HDR (heavy drive radial) rear and this is the best RV tire I have ever come across. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Loren Busch
Sent: Monday, July 18, 2011 6:44 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: understanding tire sizes

 RE: 'Ply Ratings'
As far as I've been able to determine the "Ply Rating" system is no longer in use and hasn't been for some years now.  It was a throwback to the old bias ply tires but was not a good or accurate way to describe radial tires that can be constructed a number of ways. Here is a page with a table that shows corresponding Ply vs the more current "Load Range" info:
<http://flashoffroad.com/features/Tires/loadrating.html>
and below that the more precise "Load Index" ratings.

I haven't bothered to look but is anyone aware of any modern (current
production) tires that even have a "Ply" number on the side?