Just wondered what people do when towing the caravan. We have always blown the tyres to the “full” car pressure when towing. However the car has passed mot with advisories on both rear tyres due to cracking on the inside. The tyres were five years old but still have about four millimetres of tread. We have replaced them as we would hate to have a blow out when towing. But, I wondered if blowing them up to full load pressure caused the cracks. The nose weight of the van and the awning in the boot are about 120kg.
From my experience over the last 20 years, 5-6 years is about the length of time tyres now last before cracking appears.
I had a car which was 6 years old, the original tyres had done 40,000 and were good for another 10,000, but the walls were full of cracks so they were changed.
Hi, It would help if you gave the type of vehicle and tyre make and size. My experience tends to point to under inflation of tyres. Having said that my Bridestone tyres on my car are about 4 years old and are showing age related cracks.
your caravan has a max nose weight of no more than 97 kgs this is worked out by the max loaded weight of the caravan multiplied by 7%
however, this now depends on your cars max nose weight, most are 75kgs but you do need to check in your hand book for the exact weight, this figure MUST NOT be exceeded, so for example
if the caravan allowed for 100 kgs but the car only allowed 75kgs then you can only load upto the 75kgs
so once you have got the figures, you now need to get the bathroom scles out and a bit of wood for the tow hitch to sit in and start moving equipment around to get it as close to the max caravan towing weight, to do that you do not place items in the back of the caravan, but start with the awning being placed in the middle, across the axle, then carry on placing items forward of the axle to acheive the correct weight.
your towing with 120 kgs has definately well exceeded both car and caravan limits hence why your having issues with the tyres.
car tyres should be increased on the inflation according to the figures in your handbook which should be around 36 psi but you do need to confirm that.
As to car tyre pressure, do as the car manufacturer instructs for towing, it's often the same as the 'fully loaded' pressure. - It can make a BIG difference to car stability when towing, as the trailer tends to push the rear of the car sideways under a number of circumstance, 'soft' tyres tend to 'roll on the rim' (sideways) more than 'hard' tyres. - that can be the start of a snake!
The extra load from the trailer nose weight is relatively minimal, equates to one chubby person in the back seat! - it's the reduction in tyre wall roll that is the concern. That seemingly minimal movement at the wheel is amplified by the physical laws of leverage over the distance to the tow hitch, that results is quite significant.
On age cracking, a lot of variables that can contribute. Perhaps surprisingly, lack of regular use plays a part, it's partially why caravan tyres deteriorate relatively quickly. The 'plasticisers' that keep the rubber from drying out and becoming brittle (hence the cracking) need the rolling distortion of use to keep them evenly distributed throughout the tyre. Your lack of tread wear over 5 years implies infrequent use!
I changed my car tyres (Michelin) at 6 years old, because the microcracks on the sidewalls were become obvious, not because the tread had worn out, probably a good 7-8K left before close to TWI, that's well over a year for me, I don't do a lot of miles. No MOT advisories, just caution with a view that I don't want a tyre failure at all, but especially not when towing!
The way I look at tyres is not as a big financial hit to replace a set, but as a running cost per year, mine had cost me around £90/year, which is a minor cost compared to other annual motoring costs like tax and insurance.
Quote: Originally posted by atkinbrown on 01/9/2025
Our nose weight is 90kg checked with nose weight gauge before every trip. The awning in the boot is about 28kg and that’s where the 120kg comes from.
what does your car state for the nose weight? if you dont know then just let us know what car you have and we might be able to find the figures for you.
btw you dont calculate the nose weight in the manner you have done.
Thanks for all the replies. According to this and other forums the consensus is that the tyres should be inflated to “full load” pressure when towing and that is what we will do from now on.
Always go by what the car manual says. On our previous car, there were two tyre pressures listed for the rear tyres, one for normal driving and one for towing or carrying a full load in the back. On our current car, the manual specifies the same tyre pressure for both situations so we do not change it.
Correct psi can vary between tyre brands. Some manufacturers like Continental aren't shy about telling you the recommended psi for their tyres v your axle weight. Others like Michelin aren't & will refer you to the plate.
Always going to vary by weight. Not a caravan admittedly but on our campervan Conti have recommended psi 31psi below the plate based on our weighbridged axle weight backed by an explanation why the plate PSI is so high (& would have wrecked our suspension the way it was banging over potholes)
Quote: Originally posted by spiritburner on 02/9/2025
Correct psi can vary between tyre brands. Some manufacturers like Continental aren't shy about telling you the recommended psi for their tyres v your axle weight. Others like Michelin aren't & will refer you to the plate.
Always going to vary by weight. Not a caravan admittedly but on our campervan Conti have recommended psi 31psi below the plate based on our weighbridged axle weight backed by an explanation why the plate PSI is so high (& would have wrecked our suspension the way it was banging over potholes)
I believe the VERY confused situation with MHs revolves around origins of the commercial vehicle chassis upon which they are based!
Ultimately, the correct figure is related to the ACTUAL axle load, which it seems caravan manufacturers are better at than MH manufacturers!
Really, you need to know what your actual axle loads are to determine what the correct pressures need to be. When checking caravans, the manufacturers figures seem to be close, MHs on the other hand seem to vary considerably! Plenty of MH owners seem to claim recommended pressures are spine shattering and opt for lower figures!
Quote: Originally posted by Monty15 on 02/9/2025
I believe the VERY confused situation with MHs revolves around origins of the commercial vehicle chassis upon which they are based!
Ultimately, the correct figure is related to the ACTUAL axle load, which it seems caravan manufacturers are better at than MH manufacturers!
Continental reckon the high pressures on plate are due to ETRTO assuming a MH is going to unevenly & over loaded. So worse case scenario. For Conti's figures the vans would have to be very overloaded to reach the plated pressure. They stress the importance of getting axle weights determined on a weighbridge before using their figures. Seeing the amount of stuff a lot of people carry I think a weighbridge visit is a worthwhile exercise.
I have never increased tyre pressure when towing in over 50 years of Caravans. The nose weight added to the towbar is a max of 100kg, which is less than 2 people sitting in the back seats. I am sure people do not inflate and deflate tyres pressures each time they have rear passengers and when they get out again.
Quote: Originally posted by birdman101 on 03/9/2025
I have never increased tyre pressure when towing in over 50 years of Caravans. The nose weight added to the towbar is a max of 100kg, which is less than 2 people sitting in the back seats. I am sure people do not inflate and deflate tyres pressures each time they have rear passengers and when they get out again.
Quote: Originally posted by birdman101 on 03/9/2025
I have never increased tyre pressure when towing in over 50 years of Caravans. The nose weight added to the towbar is a max of 100kg, which is less than 2 people sitting in the back seats. I am sure people do not inflate and deflate tyres pressures each time they have rear passengers and when they get out again.
Exactly this,
Missing the point of higher inflation entirely!
In the case of weight in the car, be it passengers, luggage, weight on tow hitch, or a combination of, it IS to cope with the extra tyre load if approaching the max carrying capacity.
In the case of just towing under consideration, it reduces the 'side roll' of the tyre on the rim caused by the sideways forces imposed by the trailer! It's a stability benefit, not necessarily a load benefit!
A number of things impose sideways load on a towing car, road bends and cornering, changing road camber angles, bow waves from large vehicles passing or being passed impacting the significant 'sail area' of a high sided trailer. Cross winds and gusts as well. The less the tail of the tow car 'wobbles' or moves sideways, the less the chance of a snake developing.
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Topic: Tyre pressure.
via mobile 01/9/2025 at 12:10pm
