hi will be towing later this month so will be pumping tyres up to full load pressure .then will be towing back a week later.

 

is it worth reducing tyre pressures back to normal load pressures during the week in between & then pumping them back up for the drive home or just leave them as they are

 

i know ride will be a little harder but am use to that .

 

tyres are 225/40/15 on a octavia vrs 

How many up, and what's the imposed noseweight of the trailer?

 

If you're two-up and the noseweight is under 50kg, I'd suggest there is no need to increase pressures.

sorry will be towing a folding camper (1/2 a caravan ) with 3 in the car with a boot full .so i do need full pressure 

I inflate mine when I'm towing and I always leave them up until the end of the trip.

I inflate mine when I'm towing and I always leave them up until the end of the trip.

 

Ditto.

question answered many thanks 

Loading aside, higher rear tyre pressures have another benefit when towing which is their contribution to trailer stability.  I'd increase the pressures for towing regardless of noseweight or car loading.

 

Whether a trailer goes unstable is mainly a question of whether or not it exceeds a critical speed (which is different for every outfit, but could be as low as 60mph or even lower).  What that speed is, is affected by a number of factors including the lateral stability and overall stiffness of the car's rear suspension, of which the tyre is a component.

 

The lower the rear tyre pressure, other things being equal, the lower the critical speed.

 

The other thing to check of course is the trailer tyre pressures.  On a two wheeled trailer these are likely to be higher than on a car of comparable weight, that has two axles.

 

I have a 1200kg caravan.  The handbook recommends 2.4bar.  I noticed that after a run, the caravan tyres were quite hot, so I ran them at 3.0 bar after that (within the maximum pressure on the sidewall) and they ran at the same sort of temperature, tested by hand, as the car tyres.  Around that time, the manufacturer revised its advice to 2.8bar!

 

I have a pet theory that the biggest single cause of the thankfully small number of caravan accidents we see is tyre problems, either on the towcar or more likely the trailer.  Under inflated tyres, if the pressures are well below what they should be, will overheat and fail at worst, or reduce stability at best.

 

I'd post a link to a Bath University study published years ago but it's dead now.  I have found a quote though - 

 

"the test car was known to have a fairly compliant rear end; the tow ball was

situated quite a long way behind the rear axle, and the rear suspension bushes were

known to be slightly worn. This compliancy had the same effect as having the car

rear tyres at a low pressure, i.e. it increased the tendency for lateral movement at the

tow ball point, which increased the snaking probability"

 

EDIT:  Sorry if the above is a bit tangential to to the topic. For what it's worth I usually leave the tyre pressures up in between as well - but on my tow car it's only about 4psi.  I don't use the Roomster for towing but I see the pressure differential is much higher - so I'd probably adjust them in between.

Edited 17 July, 201411 yr by Manatee

I always found my mk1 octy VRS uncomfortable to tow with at motorway speeds,

 

it always felt to soft on the rear end,

 

i picked up a ton of gravel in my little 6x4 single axle trailer and altho it was loaded even it felt really unstable, my classic volvo s40 and my peugeot 406HDi felt alot more stable with either the same or more weight,

have towed with my vrs for 3 years now & never had a problem . now have 2 brand new michelin pilot sport 3 on the back now & i will be  checking & inflating the folding camper tyres next week .

so cheers manatee its pretty much what i do . but nice to have it repeat by sombody else