Cooper S/T's Scalloping edges GU III - Any Idea's?

Submitted: Sunday, Jan 22, 2006 at 18:59
ThreadID: 29981 Views:2691 Replies:6 FollowUps:4
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G'day all, I've got a set of 265/75R16 LT Cooper S/T's on my GU III and noticed this morning that the front tyres have pronounced scappoping on both inner and outer edges of both front tyres. At this stage the truck is bog stock, apart from the suspension, and mostly running empty.

I am running 42psi in them and have King Spring and Koni's. The tyres, springs and shocks were all fitted at the same time, nearly 10,000 k's ago. The tyres were rotated at 5,000k's. I didn't notice this wear pattern when I had the first rotation done.

Any Idea's guys ???



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Reply By: Member - Roachie (SA) - Sunday, Jan 22, 2006 at 19:12

Sunday, Jan 22, 2006 at 19:12
My initial thought (before I got to the 2nd paragraph) was that your tyre pressures might be a bit low.......BUT 42 PSI is probably too high for a stock-weight GU. I run that pressure all round in my GU; but it is rather a lot heavier than a stock truck.

So sorry, I can't suggest anything really. I'd be taking them back to the tyre dealer and getting his thoughts.

I did have a set of Cooper STs and found they were wearing on the outsides too, as well as chipping badly. I solved the problem by buying Goodyear MT/Rs. Coopers will not be getting any more of my money for STs....but I may be tempted with their STTs when I change over next time.


AnswerID: 150182

Follow Up By: P.G. (Tas) - Sunday, Jan 22, 2006 at 21:10

Sunday, Jan 22, 2006 at 21:10
G'day Roachie. Just a couple of things. I am getting the perfect 4psi build up after the hours driving I do every day, running 42 front and 40psi rear. (took me 6 weeks to work that one out).

I was wondering if my Koni's might be set too soft. When I installed them, I set the 4 of them up on the softest setting and todate the ride and handling are fine. Do you think it might be worth knocking them up a turn or 2 ??


FollowupID: 403606

Follow Up By: Member - Roachie (SA) - Sunday, Jan 22, 2006 at 21:21

Sunday, Jan 22, 2006 at 21:21
Sorry Peter, I can't give any recommendation on the Konis; even though I had them on my GU for the first 3+ years. I didn't instal them myself and never knew what setting they'd been installed at. By the time I took them off, they were leaking everywhere and I gave them away and put XGS's on instead. But, the Konis were very good and I'd have another set next time maybe.
I hope you can get to the bottom of it; good luck
FollowupID: 403609

Reply By: Wayne (NSW) - Sunday, Jan 22, 2006 at 19:13

Sunday, Jan 22, 2006 at 19:13
I think that the tyre pressure is too high for a vehicle that is running empty, even full it would be too high.

This will always get a lot of post regarding tyre pressure, but if you have a problem now, and ever thing else is OK it has to be tyre pressure. The fact that there is scalloping on both sides of the tyre rules out wheel alignment and hard cornering.

Try running 36psi and see if that makes a difference.

AnswerID: 150183

Follow Up By: P.G. (Tas) - Sunday, Jan 22, 2006 at 21:15

Sunday, Jan 22, 2006 at 21:15
Wayne, thanks for your advise.

I think I've got the tyre pressure spot on, I get the perfect 4psi build up after an hours running every day. I worked up from about 34 psi and it bucked and rolled all over the place until I approached the 38-39psi mark.

Just a point, my S/T's are rated at their maximum load at 80psi (on the sidewall).


FollowupID: 403607

Reply By: TroopyTracker - Sunday, Jan 22, 2006 at 21:05

Sunday, Jan 22, 2006 at 21:05
BFG's next time? ;-)
AnswerID: 150195

Reply By: Truckster (Vic) - Sunday, Jan 22, 2006 at 21:50

Sunday, Jan 22, 2006 at 21:50
Apparently quite common on GU's according to the patrol forum, or should I say, has been discussed a fair few times in the past.

Also I agree with the too much pressure even though you are getting gods figure of 4psi, even though that is just a generic figure someone pulled out of their arse years ago.

Try letting pressure out, and see how you go.

AnswerID: 150203

Reply By: Outbacktourer - Sunday, Jan 22, 2006 at 22:25

Sunday, Jan 22, 2006 at 22:25
P.G. I have the same set-up I think (Kings HD progressive 50mm raised and Koni's). You need to wind the Koni's on at least one 1/2 turn at the front, 3/4 or 1 turn would not so any harm if you have linear springs) and at least one full turn at the rear. I've been through the exact same issue but with BFG's. This is definitely a "shock too soft issue". It could be somewhat exacerbated by your tyre pressures which seem a little on the high side to me. FWIW I have a good number of years of success in M/sport and have a good feel in the ass end for shock settings and this is what I came up with.
AnswerID: 150214

Follow Up By: johannagoanna - Monday, Jan 23, 2006 at 00:14

Monday, Jan 23, 2006 at 00:14
I'm with you there, harden your shocks (will harden your ride), and let down your tyres (will soften the ride). The ride will then probably be back to where you are now, but without further damage to your tyres - Jo
FollowupID: 403655

Reply By: Member - Captain (WA) - Monday, Jan 23, 2006 at 00:35

Monday, Jan 23, 2006 at 00:35
Hi PG,

I have ST's that have now done 56,000kms and are wearing flat. I run 34 psi but up that to 40 psi when loaded (campervan + gear). I rotate them every 5,000km, except when I got slack once and went 12,000km and then the fronts did scallop. But after rotating and another 10,000km on them, they are basiclly flat again. Even with this mileage I still have 10mm tread all round.

As others have said, try dropping your pressures. i have run 40 psi and find it too firm for daily driving. Am very happy all round with the ST's.


AnswerID: 150239

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