herald tyre pressures

[actesteve]

Hi
Despite searching google, i can't seem to find the correct tyre pressures ( or recommended) for my 1965 herald 12/50.
The recommendation in the handbook is 19psi but i am using tyres which are marked 145R13 which are radials, and i am sure 19psi is too low. at the moment, they are all at 28psi. Any sugestions?
thanks!
Steve

[heraldcoupe]

Hi Steve,
Your current 28psi is just about right. I usually run between 26 and 30psi,
Cheers,
Bill.

[Keith]

Steve,
I find that there needs to be a good differential between front and rear pressures to make it handle and prevent oversteer, I run about 24 front  28 rear.

Cheers,

Keith

[ginger948cc]

I've always run 24 allround (as i saw this in the handbook) ,but recently tried 28. It was most uncomfortable, and I was aware of rattles which had not existed before. I was back to 24 for Leatherhead yesterday ...........nice! When I  take two others in the car plus a small amount of luggage on the 10 CR I shall try 26 or 28 in the back.
The tyres are 155 R 13. (what ever that means: What is the difference with 145 R 13 please?)

[heraldcoupe]

145 R 13 is the largest that's really suitable for a standard 3.5" Herald wheel, 155 R 13 tyres on the narrow wheels are most disconcerting during hard cornering as the tyre-wall rolls - it feels like the tyre is coming off the rim, not nice at all.
If you have 4.5" (Estate, Vitesse, Spitfire) wheels or something non-standard fitted then the larger tyres won't be a problem.
Cheers,
Bill.

[Raider]

The difference between 145 and 155/80R13 is that the first part of the tyre size refers to the nominal section width in mm - hence 145 is 145mm and 155 is 155mm. The short answer is 10mm wider but it will also mean the radius and circumference are different.

The Michelin technical data book gives 145R13 as the correct radial tyre fitment on 3.5" wide wheels and pressures of 20 front and 30 rear.

[ginger948cc]

Thanks Bill and  Raider. Would 20 front/30 back be appropriate for the 155 tyres too? Many thanks!

[Raider]

Not sure.

You are OK to make small adjustments, say 2psi and see how it feels - anything from 20-24 front and 26 to 30 rear would probably be fine but be aware it will alter the handling characteristics. Also a prime function of the tyre is to carry the load imposed on it and that is down to how much air you put in it.

The load isn't going to change as much at the front as at the rear with passengers and a full boot load of luggage, spare etc.

On handling - rule of thumb is more air in the back and less in the front gives more understeer (car goes straight on when cornering), more air in front and less in back gives oversteer which could result in the rear swapping ends with the front!

All in all, probably 22 front, 28 rear wouldn't be a bad compromise

[heraldcoupe]

I wouldn't  run a Herald on radials with anything below 24psi at the front. I settled on a 26/28 slpit front to rear for a long time. I started running higher pressures on the recommendation of John Kipping and I now tend to run with 28 front, 30 rear. As far as I am concerned nothing is cast in stone and I adjust my pressures according to the characteristics of particular Heralds and the tyres fitted. Very subjective stuff I'm afraid,
Cheers,
Bill.

[Raider]

I have run my Vitesse with 24psi in the front with 155/80R13 Michelins including 2 RBRRs and a trip round the Nurburgirng.

Given that the 6 pot in a Vitesse is a heavy lump I can't see why a Herald would need higher pressures.

Over to you Ginger948 - let us know what you find.

[ginger948cc]

24  in the  front seems max to me . I'm still wanting to try 26 in the back. I'll give it a go once I get the car out  on the road again after fiddling around with things which didn't really need touching.

[Raider]

24/26 is what I ran my Vitesse at.

Supposedly the handling can be dodgy but I never found a problem - amybe I wasn't trying hard enough ;D

[Tim Bancroft]

On my GT6 I run 29 all around on 175/70 13 tyres- seems good on a track!

What about a big saloon- i run 29 on that as well>

[James]

But your 29 all round is on a more neutral handling rotoflex...

Having said that I used to run 30 all round on 165/80s on my 1500 - worked a treat...

[Raider]

On a 2.5PI the Mich recommended pressures are 26 front 30 rear.

You have to bear in mind tho that these are for 185R13 and I know your car is on 15" Tim.

Also recommended pressures are usually biased towards understeer as this is perceived as being safer than oversteer.

I would think that you can  run higher pressures in the front as there's no problem with load carrying capacity but it will tend towards shifting the handling balance towards oversteer. too much tho and you affect the contact patch which isn't desirable either.