Tyre pressure?

May 25, 2004 8 Replies

Hi!



I have a 1979 MGB GT fitted with Rostyle wheels and 165R14 tyres (with tubes). My problem is that at the manual's recommended pressure there's a distinct bulge at the bottom of all the tyres (not a very good photo):


Is this right? The handling feels fine (my other car's a Mercedes A-Class and I've ridden shopping trolleys with better road holding than one of those, so it's hard to compare).



Thanks in advance,



Carl.


In message , Carl Woffenden writes

The A Class suspension design was rejected by our group very early on after failing shopping aisle 'swerve tests'. We were hoping to reclaim some of the design costs by putting a 'tea chest' design body on.

Yours

Mmmm... I have the same problem with a 1972 roadster. Is it something to do with more modern tyres having softer walls perhaps??

In message , Carl Woffenden writes

That's standard for radial tyres, Carl. My '74 B tyres look very similar. You could maybe add another 3 04 lb/sq. inch (or whatever the metric equivalent is), which will make the steering lighter when turning in confined areas. Peter C.

Initially that's what I though - but the tyre fitter remarked that all my tyres (although the rears have been replaced) were from the early 80s (some triangle/dot/squiggle date marking thing).

Carl.

I already have - they were really flat looking before!

Metric...?! Bah, it'll never catch on!

Carl.

What's the maximum pressure on the tyres? You don't want to go too high, but equally well you definitely don't want the tyres all squishy as they will heat up and get high pressure anyway by wearing out the rubber.

I'd pump them up to "look right" so long as it wasn't too high a pressure for the tyre, and test the feel in practice. Too hard, is harsh, not hard enough is soft but slack.

We have run my '78 BGT on the recommended tyre pressures with no problems for all its life. Radials do look soft at the bottom.

John

John is right about the look. The other thing to look at is wear on the tyre. You will see the edges wear first if its under inflated and the middle if over inflated. Having owned and raced a B for 12 years now I would say the book is about right.

Simon

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