The Gates book I have in my library shows that:

"7" Series = 10mm (3/8")
"8" Series = 11mm (7/16")
"9" Series = 12.5mm (13mm)

I agree with Dennis, Gates makes a fine substitute for the OE
Continental for the WBXR (inso far as I have seen) and I have used
them in a pinch.  As I stated in an earlier post, the OE Continental
is still available, maybe not at VW, but many aftermarket sources
(such as BD and Airhead) carry them.

--
Jim Thompson
84 GL 1.9 "Gloria"
84 Westfalia 2.1 "Ole Putt"
72 411 Station Wagon "Pug"
75 914 1.8 "Nancy"
Full Timing From March 1999 To January 2012
oldvolkshome@gmail.com
http://www.oldvolkshome.com
Find me on Facebook:
http://www.facebook.com/people/Jim-Thompson/100000710343835
***********************************

On Sun, Sep 23, 2012 at 2:07 PM, Dennis Haynes <d23haynes57@hotmail.com> wrote:
> The "7" series is 7/16 or 11mm. The original belt is 10mm. I use the Gates
> 7430 for power steering and 7435 for the alternator-water pump regularly
> with excellent results.
>
> Dennis
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> David Beierl
> Sent: Sunday, September 23, 2012 3:45 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Alternator continuous-duty rating?-V-belt drive rating.
>
> At 02:36 PM 9/23/2012, Rocket J Squirrel wrote:
>>Presently running a 7430 Gates XL belt. Can I do better in terms of
>>maximizing grippage and reducing slippage?
>
> If it's a half-inch belt...our system is set up for 3/8, which is why the
> auto-parts crossreferences tend to come out short.  Otherwise Gates make
> excellent belts.
>
> Yrs,
> d