tyre pressures

[abetterlife]

Hi I'm new here - just recently bought a 1967 Herald 1200. Can anyone guide me on tyre pressures? I came to realise that the original spec was for tyres of the times... And tyres have changed! We now use tubeless tyres on modern cars... ad modern tyres are all that's available now (undoubtedly a good thing I'd imagine). But the rims of our old Heralds are not like those on modern cars, and it seems that the most common advice is to fit a tube. Which is ok with the right quality of tyre that won't chafe the tube.. How am I doing so far?

But then, what tyre pressures should I use to inflate these modern radials.. with tubes...? The old spec (19 psi front and 24 rear) is clearly too soft - so I have used to 24 psi front and 26 psi rear.  The tyres are 145 SR13. What do you do?

[Keith]

24 front and 26 back is about right, you need a bit of differential between front and back to keep the handling in check. You can go higher at the back, I run 28 on my convertible. No need for tubes, the wheels are meant for tubeless tyres and are fine as long as they aren't rusty inside. 145 x 13 are the largest radial you can fit on 3.5J rims, they have a slightly smaller rolling radius than the crossplies which gives a bit of speedo overread. 4.5 rims are standard on estates, 3.5 on saloons, coupes and convertibles.

 

[RobPearce]

24 / 26 was the book spec for cars fitted with radials. I usually run mine a little harder than that, say 28 / 30, but I'm on 155s on a Vitesse, 175/70 on the GT6.

[Scimher]

I thought that there was supposed to be 3psi between rear & front (21 & 24 come to mind...) - with that in mind I run my 1200 convertible with 30psi rear & 27psi front......135x13 tyres currently fitted on 3.5" rims, but I also used the same pressures when I had 5" Spitfire /Dolomite wheels fitted with 175/70x13 tyres!

[Clive]

Quoted from abetterlife-

Hi I'm new here - just recently bought a 1967 Herald 1200. Can anyone guide me on tyre pressures? I came to realise that the original spec was for tyres of the times... And tyres have changed! We now use tubeless tyres on modern cars... ad modern tyres are all that's available now (undoubtedly a good thing I'd imagine). But the rims of our old Heralds are not like those on modern cars, and it seems that the most common advice is to fit a tube. Which is ok with the right quality of tyre that won't chafe the tube.. How am I doing so far?

But then, what tyre pressures should I use to inflate these modern radials.. with tubes...? The old spec (19 psi front and 24 rear) is clearly too soft - so I have used to 24 psi front and 26 psi rear.  The tyres are 145 SR13. What do you do?

If the tyres really are 145SR13 that means they are extremely old. 20+ years and desperately need replacing. 

(if they are 145R13, and are date stamped less than 7 years old, then they are OK)

Date stamp info here (not a company recommendation, just the info!)  https://www.kwik-fit.com/tyres/information/tyre-age

Seems I am different to most others and on my herald ran figures the same as you are now. Likewise my spitfire I run at 24psi all round, harder just doesn't work as well on my setup.