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Hi, I have been restoring a 1988 Abbey Stafford. It is now near completion, however I am not sure which tyres will be required. Currently there are two 175 R13 'Grand Prix S' tyres fitted, which are obviously car tyres. Does anybody know what load index tyre I would need? I do not have a handbook but believe the MTPLM weight to be 1150Kg

As always, any help will be appreciated.

Advice here 

Thanks for replies, so a load index of 90+ would suffice. Do the tyres also need to be 4 ply? I have read many posts saying that 2 ply are not sufficient.

Thanks again,

In truth ply rating is out dated, ie, a tyre rated as 8ply no longer actually has 8plys?!, however, standard or car tyres are/were rated as 4ply, I've no idea what a 2ply might be? jockey wheel perhaps!!

So as said, what you need is a pair of tyres that can carry the weight of the van with an extra margin of 10% or a little more, whatever that tyre happens to be.

According to My Abbey Manuel A 1993 Abbey Stafford Tyres are quoted as 175 R 13 6 ply R  Tyre Pressure 54

Once again, thanks for all your help.

Duff info removed , sorry .

atb

Wizard

Point of order Wiz! you got this info off Tyreline? 

'your tyres' are 6ply so 1340kg at 54psi, 8ply should be 1460kg but at 65psi. At 1160kg on 6ply correct pressure would be 51psi and the tyres a bit under spec!, 8ply and correct pressure is 49psi

So this van if changed to 165x13 would need the 94 load index (8ply) and as it happens needing 54psi for 1150kg

If you stick with 175x13 then still 94 load index but a 6ply and needing 45psi

Hi Gary , thanks for spotting my duff info , i got the info off the tyre but it should be 670kg ( 1375lbs ) at 54psi.

And this My caravan weighs approx 1160kg when fully loaded and i inflate the tyres to 42psi . should read inflate to 47psi .

Worked out this way Calalated using the tyre Load index 92/94N which says 54psi at 1340kg for a 175 R 13 6ply . So i did 54 divided by 1340 = 0.040298507 approx
Then times 0.040298507 by 1160 mtplm of my caravan = 47psi

I'll have to check my info better next time

atb

Wizard

I also made an error, (got 165 mixed up with 175!!), your actual correct pressure is 45psi, the caculation is not accurate but always gives a higher pressure making it safe, hence your 47psi

Where the calculation really does fall down is the further from the tyres maximum weight the actual weight is, so if the van only weighs half what the tyres can carry, it becomes far to high, perhaps 7psi or even more!!

In the absence of a pressure chart it's still probably going to be better than guessing and because it's always high the tyres certainly won't overheat, but, will give the van a far harsher and bouncer ride that need be.