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Thomas-the-Terrano2
02-03-2012, 09:30
Just had caravan serviced and whilst tyres were in good, condition
still 3 years on from dealer fitting new when bought caravan.

Lookig at their spec they are budget car tyres 155/80R13 79T

so 79 = 437kg and T = 118mph,as if !

The chassis is rated at 1660kg, 4x437 is 1748kg so is more but
not by much, the 'correct' commercial/ply types are typically
500 kg loading each, much more.

Wondering what margin should be as if I over load chassis ok
its a crime, but wont take much to overload tyres assuming
they get evenly loaded over the two axles.

Fore ref the 106 T on the truck equate to 3800kg combined
v its gross of 2580kg!

gazterrano
02-03-2012, 11:11
Just had caravan serviced and whilst tyres were in good, condition
still 3 years on from dealer fitting new when bought caravan.

Lookig at their spec they are budget car tyres 155/80R13 79T

so 79 = 437kg and T = 118mph,as if !

The chassis is rated at 1660kg, 4x437 is 1748kg so is more but
not by much, the 'correct' commercial/ply types are typically
500 kg loading each, much more.

Wondering what margin should be as if I over load chassis ok
its a crime, but wont take much to overload tyres assuming
they get evenly loaded over the two axles.

Fore ref the 106 T on the truck equate to 3800kg combined
v its gross of 2580kg!

could be worth considering 6ply as apposed to 4ply which will prob be on now, the walls much stronger made for extra load not so sure on exact weight capacity as ive not been in tyre game now over 10yrs, used to fit lot of 6plys on vans in some cases some customers wanted 8plys but by the time your loaded up with fair run ahead the rubber soon gets warm

MudLifeCrisis
02-03-2012, 12:56
My twin axle is fitted with 82H tyres so rated for 475 kg and 130 mph. The van max weight is 1650 kg. These are replacement tyres but the same rating as the originals.

What van do you have? If it's Explorer group they have an archive section on their website that gives tyre details.

Brian

Just to add mine are 175 65 R14

andrewk
02-03-2012, 13:22
Another issue here is that if you replace the car tyres that were on the caravan from new with 6 or 8 ply reinforced or commercial tyres, the side walls are stiffer and they run hotter unless you set a higher inflation pressure. Running much hotter could increase the risk of failure. Have you measured the difference between the cold tyre pressure and hot pressure? Ideally, the difference should be around 4psi. (Try Googling "4psi rule")

For caravans, the tyres are an integral part of the suspension - so you will affect both the suspension dynamics and the road shock transmitted into the caravan chassis and body.

In the context of caravanning as a whole, the cost of replacement tyres isn't that great. I'd be tempted to go for similar tyres to those fitted by the manufacturer when new i.e. car tyres - but of the highest load rating you can find.

Andrew

gazterrano
02-03-2012, 13:50
there are lots of vans on reinforced 6 & 8ply tyres these days ,unlike your personal car most vans run neglected overweight most not serviced regulary & in most cases expected to run flat out down motorways flat out , my van used to be on reinforced normally run at speeds of 55mph to norfolk 160 miles never a worry or problems as i knew the tyres could cope well, speed was never excessive the weight was well within the limits no heat build up . most caravan tyre problems i used to see was down to perishing where the vans been stood mths or yrs leaving the tyre sidewalls cracked & perished then expected to cope with motorway travel , ive seen some been almost close to being on fire due to little pressure & weight that have finally given up then they wonder why they almost lost the car & van

Thomas-the-Terrano2
02-03-2012, 14:02
tin tent = my99 abbey spectrum 520 ta

520 = 5 berth 20 feet

plate on body only gives ynladen and max aut weight,

1377 and 1660kg respectively.

want to find each axle load as suspect combined will be
good bit more than the 1660 so likely tyres illegal per axle.

going to email caravan dealer, get in writing their stance.

will check trailer's manual later too.

rustic
02-03-2012, 18:58
You have all missed the important point regarding tyres on twin axle trailers.:nenau

The side wall on these tyre have to be reinforced because on tight turns, the tyres are trying to be ripped off their rims, this happens when reversing on full lock or doing tight "u" turns.
This happens because the wheels are close together, and if you look at the tyres when turning tight, the front tyre will be scrubbing one way, and the rear tyre the opposite way.

If standard tyres are used, then unseen internal damage can occur to the side plys, which could lead to tyre failure.:eek:

When I reverse my boat down a slip way you can see it.

Thomas-the-Terrano2
02-03-2012, 19:18
well i'll go to the foot of our caravan steps!

dug out the abbey handbook an it quotes

155R13 78T, @32psi.

so a 78 is less still at 425kg, 1700kg in all and
only 40kg more than MAM. But hey can haul
it at upto 118mph still so got to be safe at
half that?

reckon its time to cull the excess weight we
carry a fair bit of stuff probably never use.

Thomas-the-Terrano2
02-03-2012, 19:24
agreed rustic about, scrub, only got to see a twin or tri axle artic
trailer scrubing, leave rubber on road.

only thought is keep speed down and keep lock to minimum when
doing such moves

certainly can feel resistance if move twin axle by hand, whilst it
rolls well for its weight, it doesn't want to turn a corner.

mind if off vehicle an old trick is max out the jockey wheel to
reduce load on leading axle but thats surely a lot of strain on the
jockey wheel.

(RIP) PLANK
02-03-2012, 19:50
I agree with the side forces on TA tyres, I've learnt that lesson the hard way!

and I also agree the idea of winding jokey wheel to the max is often suggested but in reality impractical, likely to bust the jockey wheel and for a lot of long caravans the back end would be on the floor before you made any real difference to the front axle. The jockey wheel does not have much of a lifting capacity then imagine the force on it when you try to turn the caravan sideways :doh

I would fit 6 ply tyres, generally 6 ply are marked 'reinforced' and 8 ply as 8 ply.

Thomas-the-Terrano2
02-03-2012, 23:23
oh well when these need renewing I'll consider heavier
though wonder if there'll be any kick back from insurer
if not factory spec, even though 'better than'.

funny with troll as ratio was so good way less than the
85% had wondered what it would cost to replate
caravan heavier to make sure didnt overload it and maybe
have extra batteries on board. Now realise would need
much higher capacity tyres, maybe rims too to consider
it.

BUT as T2 is lighter and the match is 85% won't bother!

Quite fancy getting caravan on a weigh bridge as really
don't fancy weighing every cup and plate....