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MG MGF Technical - Tyre pressues

I have an Abingdon VVC with 16" alloys fitted with Goodyear Eagles,

I have a couple of inside wall failures on rear wheels, luckley both at low speed.

Investigation suggests that these may be due to long term low pressure running, some alloy porus leakage???, but I began to look at the pressure that I have been running the tyres, and I find that I am being given two pressures for the rear wheels, 36 psi in the handbook, and 26 psi in an adendum to teh hand book.

Can anyone confirm what pressure I should be running, 26 sounds low to me and could be the cause of teh tyre failure??

Thnaks

Jon
Jon Osborne

Jon
The manual states 24F and 28R for the 16" wheel and tyre.

I run my VVC (15") at 28 all round and the handling is good and sharp.
Tyre wear on the inner edges could be incorrect tracking, BUT the place to start is to have the hydragas level checked for correct height.
Should be 368 mm from centre of MG badge on front wheel to wheel arch lip +/- 10mm at 17deg c.


HTH

TH
Tony Harrison

Hi Jon,

Check carefully that the figures you're using are for the specific tyre on your car - different tyres can require wildly differing pressures.

The Goodyear Eagle F1 tyre comes in two flavours - GSD2 pattern and the later GSD3 pattern. The GSD2 has a soft sidewall and relies on quite high pressure to keep the tyre in shape, hence 36psi at the rear. Running the tyre significantly below this long term will degrade the sidewall prematurely, as it seems you've discovered. The later GSD3 pattern has a stiffer sidewall and doesn't need help from the air pressure, so 28-30psi works fine.

If you have the GSD2 pattern F1s, I've experimented with a wide range of pressure combinations on track days, and I've proved to myself that 36r/28f is indeed the best (i.e. safest, most predictable) combination, and altering either end significantly leads to unexpected excursions into the greenery & gravel traps 8-/ It seems MGR didn't just pluck figures out of the sky, they are actually correct...

Mike Hankin

I agree with you Mike. Run 28psi all round with the 'D3s and ran 30psi all round with the 'D2s... :o)
Rob Bell

Thanks to the response, still not totally clear what pressures I should be running, as I have GSD2's it seems it should be something a lot higher than that I am currently running.

Better get that foot pump out!

Thanks
Jon Osborne

What would people thing would be right for Toyos fitted to 15inch rims?

Gary

28 all round.
Tony Harrison

go 28 front
30 rear

for best handling.

tyre presures are weight related.
r.f.j. griffiths

30 psi for GSD2 on both 15 and 16 inch wheels ?
Jon Baker

This thread was discussed between 09/10/2006 and 10/10/2006

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