20” Tyre Pressure
- Thread starter BognorMotors
- Start date
New van with 20”. I’m trying 43 all round to start with and keeping an eye on the wear. I also took it to a Hunters alignment place to make sure it was all pointing in the right direction. Pleased to say Toe, camber and castor were green.
My only thought is, should the rears be a lower pressure?
My only thought is, should the rears be a lower pressure?
I'm not sure if this applies to 4 wheeled vehicles, but on my motorcycles I will measure the difference between the tyre pressure when hot and cold. If it goes up a few psi thats good. If it goes up a lot, means the cold pressure was too low. If it doesn't go up at all then the cold pressure is too high.
40 is the sweet spot on 20's, as advised by @BognorMotors 
I think Oli @BognorMotors is now down to 36psi40 is the sweet spot on 20's, as advised by @BognorMotors
That's interesting, I'll give it a spin at 36 and see how it feels.
I had 20” fitted and the garage put 45 psi and I found it to be to hard as I am also running B14’s.after reading Oli’s comments, I then lowered to 36psi and found it to be more comfortable and responsive.
The front and rear tyre pressure recommendations for standard 16”, 17” and 18” tyres, when the van is fully loaded is the same pressure front and back. With two people and a suitcase (vw sticker on doorway) the rears are alway a fair bit lower than the fronts. Is anybody else thinking 20” rears without a full load should be lower in pressure?
Yes, we are down to 36psi, tyre wear seems better at this pressure and obviously a better ride.
The size or shape of a tyre shouldn't make any difference to recommended pressures. The pressure of the air is what is required to support the weight of the vehicle, so it makes no difference what size vessel it's contained in.
When towing, you only need to account for the trailers nose weight, so even with 100kg nose weight, it's only like having 4 bags of cement in the back. Would you increase the pressures for that?
When towing, you only need to account for the trailers nose weight, so even with 100kg nose weight, it's only like having 4 bags of cement in the back. Would you increase the pressures for that?
Not completely true. A tyre with a stiffer sidewall will need less air pressure inside to provide the same support as a softer tyre wall.
Bigger sidewall tyres have more flex in them than low profile tyres, so again this will affect the pressure the tyre will run at.
if you are getting close to the tyres maximum load; because of your rear axel weight when towing and loaded; then you may need to consider upping the tyre pressure a bit towards the maximum inflation pressure (printed on the side of the tyre)
Because most tyres can only carry their maximum load at maximum pressure.
If you have any doubt, especially when towing (as the lateral stresses in the tyres are increased also), always go higher with the tyre pressures (particularly the rear axel) imo and experience.
The nose weight of the caravan actually increases the weight on the rear axel by more than a nose weight scale would suggest.
100kg of nose weight actually adds around another 30kg (so 130kg ish) in total because it redistributes weight from the front axel to the rear as well; because the tow bar has a cantilever effect.
If in any doubt up the tyre pressures (rear axel), and/or pop along to a public weigh bridge in full running weight with caravan attached and weigh your rear axel; by driving onto the bridge with your front axel and weight that; the move forward so that both van axels are on the bride (not the caravan axels) weigh that. Then 2nd weight-1st weight = rear axel weight.
It's a pita, but caravan towing can carry an increased risk when tyres are concerned......... I know too well from personal experience.
Because most tyres can only carry their maximum load at maximum pressure.
If you have any doubt, especially when towing (as the lateral stresses in the tyres are increased also), always go higher with the tyre pressures (particularly the rear axel) imo and experience.
The nose weight of the caravan actually increases the weight on the rear axel by more than a nose weight scale would suggest.
100kg of nose weight actually adds around another 30kg (so 130kg ish) in total because it redistributes weight from the front axel to the rear as well; because the tow bar has a cantilever effect.
If in any doubt up the tyre pressures (rear axel), and/or pop along to a public weigh bridge in full running weight with caravan attached and weigh your rear axel; by driving onto the bridge with your front axel and weight that; the move forward so that both van axels are on the bride (not the caravan axels) weigh that. Then 2nd weight-1st weight = rear axel weight.
It's a pita, but caravan towing can carry an increased risk when tyres are concerned......... I know too well from personal experience.
Tony Sneath
New Member
My T32 shuttle has these tyres.
On the tyre, it says Max pressure 50psi
On the tyre, it says Max pressure 50psi
