Tyres

[ewj]

My Herald Convertible has 145SR13 74S tyres with no profile ratio as found on modern tyres indicated, would something like a 145/80R13 fit without affecting the accuracy of the speedometer? 

[RobPearce]

Yes. Radial tyres with no declared profile ratio are usually 80 profile.

[ewj]

Rob

Thanks for your help.

[Scimher]

I have been looking at this question as I have to replace 4 very old 135x13 'retread' tyres on my 1200 convertible. I read somewhere, years ago, that the 135 tyre was the nearest to the 5.20 crossply. This has subsequently been discounted, I believe, as even the full profile 145 tyre is supposed to be a fractionally-less rolling radius than the original 5.20 crossply tyre. 

It would appear that the 145 profile tyre is the way to go on the original 3.5" rims.......with 155 being saved for the 'Estate' rim...ie. 4.5" one. There was never a 4" rim, was there?? Certainly Longstone Tyres recommend 145 tyres for the original wheels...

Before low profile tyres became the norm, tyres tended to be full profile which was '82' - full profile tyres now tend to be '80' - which is sometimes mentioned on the tyre casing, but usually not.....   

[Rosbif]

I have 155/80 fitted to my 13/60. 155 is the max for the standard rim. As for rolling radius, I don't know but the speedo is pretty accurate (when not bouncing about ! 😄)