Tyre Pressures

Colin Dav replied on 31/08/2019 18:53

Colin Dav

Posted on 31/08/2019 18:53

Hi everybody. New to caravanning here. Just a basic question really. My Mk2 S-Max has normal everyday running tyre pressures of 35 psi all round.

When towing the indiscated tyre pressure should be 41 psi front and 45 psi rear. I plan to do a number of long weekend trips with the van.

The question is, How does everybody manage tyre pressures, Do you pump thgem up and then klet them back down when you reach your chosen site.

Does anybody have their own tyre inflator and if so can anyone recommend a good accurate reliable one.

Thanks all

Colin

53 replies

redface replied on 08/09/2019 21:52

redface

Caravanner from Kent

Posted on 08/09/2019 21:52

The whole point about tyre pressures is that if they are overinflated then wear is on the centre of the tyre and the reduced footprint gives less grip. If under inflated then wear is seen on the corners of the tyres. All leading to a premature MOT failure.

When towing, a caravan will surely add more pressure to the rear wheels and less to the front thus needing an adjustment to tyre pressures so as to correct the imbalance and increase safety?

I adjust pressures every time to be on the safe side.

lornalou1 replied on 08/09/2019 22:12

lornalou1

Caravanner from Lancashire

Posted on 08/09/2019 21:52 by redface

The whole point about tyre pressures is that if they are overinflated then wear is on the centre of the tyre and the reduced footprint gives less grip. If under inflated then wear is seen on the corners of the tyres. All leading to a premature MOT failure.

When towing, a caravan will surely add more pressure to the rear wheels and less to the front thus needing an adjustment to tyre pressures so as to correct the imbalance and increase safety?

I adjust pressures every time to be on the safe side.

Posted on 08/09/2019 22:12

That's what I have been saying that putting a caravan on a towball adds 100kg max to the rear of the car which is not a massive weight so why add air. If I filled my tank I would be adding more than the caravan would be adding and I don't add air when I fill the tank and deflate when tank is nearly empty.

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replied on 09/09/2019 06:51

Posted on 09/09/2019 06:51

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richardandros replied on 13/09/2019 07:47

Member

richardandros

Caravanner from East Yorkshire

Posted on 09/09/2019 06:51 by

LL don't forget that that 100kg is multiplied by the distance the tow ball is from the centre of the rear axle, and the added side loads need to be taken into account. These all add stress to the side walls increasing flexing and creating heat which is the biggest tyre killer. I have always thought tyre pressure monitors to be a waste of space and cause of unnecessary angst, however, I would appreciate a tyre temperature monitor.

Posted on 13/09/2019 07:47

Agree DD. Incidentally, the Tyrepal system does provide tyre temperature readings as well as pressure and I have found it to be fairly accurate as compared with the air temperature reading in my car. Having suffered a blow-out on a boat trailer being towed by my Disco, some years ago - and I didn't even know it had happened - I am now a big fan of TPMS systems on trailers.

After returning from the dealers with our new caravan, I was unfortunate enough to get a nail through one of the tyres which caused a slow puncture. The TPMS alerted me and I was able to drive slowly for the remaining 5 miles to home, without doing any damage - which probably wouldn't have been the case if the system hadn't been fitted.

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lornalou1 replied on 13/09/2019 17:37

lornalou1

Caravanner from Lancashire

Posted on 09/09/2019 06:51 by

LL don't forget that that 100kg is multiplied by the distance the tow ball is from the centre of the rear axle, and the added side loads need to be taken into account. These all add stress to the side walls increasing flexing and creating heat which is the biggest tyre killer. I have always thought tyre pressure monitors to be a waste of space and cause of unnecessary angst, however, I would appreciate a tyre temperature monitor.

Posted on 13/09/2019 17:37

Sorry, I know I am a bit thick but if I weigh my tow hitch on a scale then that must be whatever it says. I know the pivot point is the axle but how can the stated weight be different, 100kg 10 foot away from the pivot point is the same as 100kg 20 foot from pivot point. Please explain as the way you say it is multiplied so 100g 10 foot away equals 1000kg seems very wrong.

lornalou1 replied on 13/09/2019 21:20

lornalou1

Caravanner from Lancashire

Posted on 13/09/2019 21:20

Just had another think about this and come to realise MM that your talking car tow to car axle and I was thinking van tow hitch to axle. Sorry again MM.

EmilysDad replied on 13/09/2019 21:50

Member

EmilysDad

Caravanner

Posted on 13/09/2019 21:20 by lornalou1

Just had another think about this and come to realise MM that your talking car tow to car axle and I was thinking van tow hitch to axle. Sorry again MM.

Posted on 13/09/2019 21:50

MM? I didn't say a word 😉 Did you mean DD? 👍

ocsid replied on 14/09/2019 07:35

Member

ocsid

Caravanner from Hampshire

Posted on 31/08/2019 21:39 by EmilysDad

I'd not drive solo with higher tyre pressures .... your car will be all over the place. I leave tyre pressures at the lower pressures for towing, after all you should only be adding 75 to 100kg (ish) to the back of the car.

Posted on 14/09/2019 07:35

Increasing the tyre pressures when towing, where the vehicle maker states doing so, is most unlikely to be due coping with the modest weight increase from the noseweight.

It is much more likely to be to increase the lateral stiffness of the vehicle to better control towing instability. The tyres being both a major contributor to this desirable feature, and the only one you can influence.