Cupping or scalloping of 'van tyres.

Submitted: Saturday, May 28, 2011 at 16:58
ThreadID: 86604 Views:5813 Replies:7 FollowUps:6
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I 've noticed the tyres on my van have become quite "cupped", I'm running 16 x 8 BFG's on a 1950kgs GVM van with trailing arm "Comfort Rider suspension, most of my Ks are on the black top at under 100kph.
I did a Google search and found no two reasons given were the same, they ranged from repeated heavy braking, wheels out of alignment, bent axles, bent rims and so on none of which I believe are the cause, does anyone think they know the real reason ???

racinrob
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Reply By: oldpop - Saturday, May 28, 2011 at 17:17

Saturday, May 28, 2011 at 17:17
Hi racinrob

Sounds like it needs new shockers

Regards

OLd Pop
AnswerID: 455715

Follow Up By: racinrob - Saturday, May 28, 2011 at 17:31

Saturday, May 28, 2011 at 17:31
Thanks O P, I've changed the tyres and now will also change the shockers.

rr
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FollowupID: 728632

Follow Up By: the redbacks - Saturday, May 28, 2011 at 18:50

Saturday, May 28, 2011 at 18:50
A picture woul have been good to view, but would also change the bearing's ??

cheers
Redbacks
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FollowupID: 728639

Reply By: Member - Andrew L (QLD) - Saturday, May 28, 2011 at 18:59

Saturday, May 28, 2011 at 18:59
What tyres are you actually running on the van..?..

16 x 8 BFG's don't exist. Are the rims 16 x 8" or 7" and with what size tyres..are they correct for the rim width.

A few more questions that may help us, what tyres pressure are you running, we know the van weight, and what is the tyre carcass and tread pattern (HT, AT or MT) of the BFG's..?

Finally, have you ever rotated the tyres (swapped sides)..ie..changed the rotational direction..?

Thanks.
AnswerID: 455725

Follow Up By: racinrob - Saturday, May 28, 2011 at 20:10

Saturday, May 28, 2011 at 20:10
Red face Andrew ! Too soft to go outside in the cold and actually check the tyres which after looking just now I find aren't even BFGs (apologies to Mr G) They are Dunlop Adventurers 235/70 R16 s which I ran at 45 lbs. My van is twelve months old, 17'6" long, not a tandem ,the tyres and rims are original and have covered about 10,000 Ks and no, I haven't rotated the tyres. It trails perfectly and the bearings are good.

Last week I pulled the Dunlops off when I noticed the cupping and fitted a pair of 265/75 R16 Cooper tyres and rims (Sunraysia's) which came off my 'Cruise, I'll see how they go.

racinrob VKE-237 Sel 6678
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FollowupID: 728645

Follow Up By: Member - peter f (VIC) - Sunday, May 29, 2011 at 18:56

Sunday, May 29, 2011 at 18:56
another thing to remember is always balance wheels ,even on trailers an c/vans
a badly out of balance wheel will cause the wheel to bounce up an down on the
ground . the heaviest part will hit the gorund hardest .
cheers mechpete ,
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FollowupID: 728749

Reply By: Member - JohnBee (VIC) - Saturday, May 28, 2011 at 19:16

Saturday, May 28, 2011 at 19:16
Gday...

Thankfully, I have only seen this problem on other people's vans and not my own .... but are you sure that these causes are not to blame .......
"I ...... found ......wheels out of alignment, bent axles, bent rims and so on none of which I believe are the cause, does anyone think they know the real reason ???"

If you haven't actually checked the axles for 'trueness' this may be the cause.
If this a tandem axle van, it is only tyres on one side - or a tyre on one side? If all tyres on both sides are scalloped then that is completely different story - tyre pressures etc may be cause .... but if all tyres are the same, I doubt if it is the tyre construction.

Also, even if not 'bent' the axle may have not been 'truly' attached to the chassis on construction - therefore 'out of alignment'.

Others have postulated good suggestions ...changing the tyres may not be the solution - may just mask the problem until the scalloping re-appears.
Cheers
John

AnswerID: 455727

Reply By: Member - DAZA (QLD) - Saturday, May 28, 2011 at 19:25

Saturday, May 28, 2011 at 19:25
Most caravan manufacturers don't balance the wheels.

This will contribute to Tyres and Wheel Bearing wear


Cheers
AnswerID: 455728

Reply By: Trevor R (QLD) - Saturday, May 28, 2011 at 21:09

Saturday, May 28, 2011 at 21:09
Hi racinrob,

You say the van is 1950kg, is this the compliance plate weight or the actual weight as weighed on a weigh bridge by yourself? The two weights can be very different, causing big problems with scalloping if so. My van was 1970kg on the compliance but actual weight fully loaded turned out to be closer to 2500+kg. For me altering tyres to cope with the "actual"van weight fixed the scalloping problems with my van but obviously I still had the weight issues and compliance plate to address (that's a whole nother story).

Hope this helps,
Trevor.
AnswerID: 455734

Reply By: Member - Leigh (Vic) - Sunday, May 29, 2011 at 07:46

Sunday, May 29, 2011 at 07:46
Hi. May I suggest you consider replacing the bushes that hold the trailing arms to the chasis. If these have deterioted you may not necessarily notice it when stationary but under live conditions it could be allowing the arm to loose it's alignment and cause your problem. Changing these would be a service rather than a structural issue. Cheers
AnswerID: 455745

Follow Up By: racinrob - Sunday, May 29, 2011 at 07:54

Sunday, May 29, 2011 at 07:54
Thanks Leigh, that's one thing I hadn't thought of, as the van is relatively new I took for granted the trailing arm bushes were in good condition, I will check them out.

rr
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FollowupID: 728679

Reply By: Member - John B2 (VIC) - Sunday, May 29, 2011 at 08:00

Sunday, May 29, 2011 at 08:00
I had Dunlop Adventurers on my old GQ Patrol and they did that also.

A lot of people had the same problem, IMHO not a good tyre.

Tyres were balanced and alignment was correct still did it.

Cheers,
John
AnswerID: 455746

Follow Up By: blown4by - Sunday, May 29, 2011 at 14:45

Sunday, May 29, 2011 at 14:45
I agree. Some tyres, usually the lower quality variety with poor quality control during manufacture, sometimes just wear like that for no logical reason. Obviously you have to check all the mechanical reasons that have been suggested, and I wouldn't just replace the shockies, check them for oil leaks and test them first. You say the van weighs 1950kg which is nearly 1000kg per tyre or more if the van weighs more. Personally I would fit an 8 ply light truck tyres for that load as the construction of LT tyres means less flexing and you can pump them up 65PSI to prevent "bouncing". Not suggesting you ran at that pressure all the time if you don't need to but you can experiment with different pressure to find what suits best. Also car tyres are not rated to carry 100% load 100% of the time but LT tyres are.
The problem of scalloping also occurs on road trains and the problem is a bit like shoulder wear when your wheel alignment has been out of adjustment........once they wear like that you cannot stop it continuing so you have to find & correct the reason and then replace the tyres.
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FollowupID: 728716

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