Tyre Pressure

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Prof
Founder, Choppers Australia
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Joined: Sat Oct 22, 2005 3:54 pm
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Tyre Pressure

Post by Prof » Sat Sep 29, 2012 9:54 am

Opinion on rear tyre pressures is usually at each end of the pole!

In the sixties/seventies we ran 15 - 20 PSI in our rear 5 x 16's. this gave a softer ride. The 5 x 16's were introduced into the american scene to compensate for rigid frames on rough roads of the time. They were called 'balloon tyres' as they replaced the skinny 3"-3.5" x 20's and 21's commonly on bikes.

However I've not yet spoken with a motorcycle tyre fitter who believes this.

Well, I was reading my 1942 WLA users manual and there it was in plain view... tyre pressure 12-18 PSI!

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Modern tyre manufacturers recommend running 5" tyres at 30 - 40 psi... the main reason being given that high speed riding heats the tyre much more at lower pressures leading to possible failure and possible tube creep.

I agree that the tyre will flex far more at lower pressure and get hotter and therefore wear quicker.

But I have always run my rear 16's at a max of 20 PSI unless heavily loaded where I'll take it up to 25. These tyres have been on a CB500, CB750, 81 shovel and 82 Sporty. My father ran 16's on a number of CB's at similar pressures... all rear sprung bikes I note the following.... 1. Softer ride, 2. fuller tread wear not just a narrow strip up the centre. 3. More tread on the grougnd for cornering and especially for braking.

I run the cheaper 16's and have had no tyre failure except on one brand that developed fine cracks in the side wall but was fine until it ws worn out... can't remember which it was though... but was one of the more expensive ones.

If I go cracking through the corners I will notice extra movement at the rear, but I don't do that a lot and consider it a small price to pay for a smoother ride and fuller tread wear (less frequent tyre replacement and a rounder profile for longer).

As I said at the beginning, opinions vary greatly, but if you are a chopper rider consider the merits of lower pressures ...
Chopit'nrideit... Prof

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