Hi All
I run a wd16H with Dunlop Gold Seal K70 3.25" X 19" tyres (made in Japan!)front and rear. In all the handbooks I've seen there are no tyre pressures quoted. After consulting Dunlop load and pressure tables from the war period I decided on 18 psi front 23 psi rear. This seems to give a perfectly satisfactory result.
However I seem to remember an Avon tyre guy giving a talk in which he said modern copies of old tyres should be run at a higher pressure than in the day, however he didn't mention any actual figures.
Are there any tyre experts out there who can confirm this and can they give any actual figures?
In Hope and Anticipation
Keith H

Hi Kieth, I've done a lot of miles on K70s as they are my tyre of choice for the M20/21 etc....I run them at higher pressures..About 26-27psi in the front and 28-29psi in the rear...
Fully loaded for Normandy, for example, with everything I need to survive on the back I find the stability is best with 30-32psi in the rear and about 28psi in the front...
This is like most things though...I know you will get varying opinions, all equally valid...
All I can say is you won't have any problems at the pressures quoted above..Just where you decide you like it is a fairly subjective thing (though over or under inflation 'in extremis' wouldn't be good....)

Obviously tyre pressures, along with valve timing marks, piston clearances, valve guide clearances and other information can be found in the very useful Norton publication...'The Big Book of Secret Specifications'.....Not available from your Norton dealer... ....Ian

email (option): ian@wright52.plus.com

Keith, this has come up on here before, and on other forums.

It seems that Avon are quite big on the modern sidewall construction idea and recommend higher pressures. Dunlop started to change back in the 1970s but at some point after all their tyre production moved abroad, they sort of forgot that they'd ever made any changes and the UK technical sales people are so far removed from the production and testing (and so paranoid about liability) that they simply hand out the 'manufacturer's literature' disclaimer which is really not good enough.

We don't really know if the K70s made now have the 'modern' (in so far as a crossply can be modern)construction or if they've reverted to their original 1950s specification.

In practice, with bikes this slow and bearing in mind that we're not riding at the limits, there is probably a fair lee-way and with a bit of luck we're experienced enough to build up slowly and not take an unknown WD side-valve to its limits on a trackday without exploring the roadholding and handling under various conditions first.

My tyres are 3.75 and I put 30psi front and back and forget about them

email (option): horror@blueyonder.co.uk