Lambda tyre pressures

[davidwheeler]

Just a thought - at what pressure do you run your tyres?   On the Weymann saloon (500/425x20) I have come down, over the uears, from 40 to 25 front and 28 rear.  This is because I always seem to wear out the middle of the tread.  On the Australian torpedo (600x22 - damn these Colonials) I am currently at about 30 all round.  Tyres are so expensive I would like to know the correct pressures!
David

[JohnMillham]

I don't know what's "correct", but I use 35 p.s.i. all round - and find that if I use less, the tyres have a tendency to squeal at the slightest provocation. They seem to be wearing out evenly. I have know people to happily use even higher pressures.
 Regards, John

[johnturner]

I have always run my tyres (20" well base) at 30psi and this seems to produce reasonably even wear, and I reckon he same would do for the Bibendum.  A contemporary Michelin catalogue recommends that the 765 x 105 tyres fitted to the early cars should be run at 45 psi and the 775x145 so called 'Confort' fitted to the 6th and 7th at 22psi, which is presumably why they flew off the rim and were such a disaster that they were quickly abandoned.  A Michelin depot man once told me that Michelin would offer to rebuild your wheels to 14x50 if you bought a set of new Bibendum tyres.  Dunno what pressure you're supposed to run the 22" but I bet Kim Brownbill will have a view and we might ask him when he is over next week.


John

[Sebastien]

My early Lambda torpedo is fitted with beaded-edge tyres (Waymaster 820x120), and I learned about tire pressure the hard way!

When in the first months of ownership I decided to have the old cracked and worn Dunlop tyres exchanged, as their appearance did not encourage driving on longer distances. After this was done I took the car out for a spirited drive, happy to  be safe on 4 brand new tyres, and in a sharp uphill turn taken enthusiastically both new rear tyres sprang over the rim!!! After a big swerve, the 2 rims dug themselves into the hot asphalt, and the car stopped undamaged. I had to get the car towed away (only one spare wheel!), but no serious damage was done. The tires could be reused, only 2 new tubes had to be ordered. The fitter had presumably inflated the tyres at a normal pressure, 2 bars, around 30 psi, which is clearly not sufficient, and I did not question his knowledge of beaded-edge tyre!

So I am careful now with tyre pressures on the Lambda, and check them regularly.
I use 3.5 bar (50 psi) which I find sufficient.

The supplier gives a maximum load factor for that tire as 585 lb @ 75 psi, 5.2 bar, but this high pressure seems really unnecessary, and could even be dangerous, if the edges of the rim are not rounded enough, and I was told that cut sidewalls are not uncommon.

Finally, I found a small booklet that can be downloaded on the Vintage Tyre Supply website, which give a lot of useful information on tyre pressures, and fittings. This booklet gives recommended pressures for beaded-edge tyres, according to diameter and tyre load, and for the 820 x 120 dimension, for 300 Kg wheel load, they give 60 psi (4.1 bar).

Sebastien

[donw]

On 19" well based wheels I have run at 30psi all round with no problems for over 20 years.

the 880x120 beed edge on the Theta run at 70psi as fitted by Longstone tyres.

Don

[Sebastien]

Don,

That is interesting info.
So now I have a lot of possibilities for my beaded-edge 820x120:
45 psi as per early Michelin catalogue, but for the smaller dimension
50 psi which I use
60 psi which is VTS recommandation
70 psi used by Don (I assume the Theta is heavier than the Lambda!)
75 psi for the maximum load of 585 lb per tyre (times 4 and you have approx. the weight of the Lambda + 2 passengers)
 Any comment, or other experience?