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Discussion Starter #1
The front tyre on my K1200LT has done about 3500 miles and it has developed bulges on the tread (raised lumps.)

The previous tyre did exactly the same thing and somebody suggested it might've been caused by over-zealous application of the front brake.

I was aware of that with this tyre and I tend to use the back brake (relying on the linked system to apply the front brake) and use the front brake only during the last few mph before I stop.
 

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Discussion Starter #2
Now the questions (I finally managed to attach pictures ;))

Does anybody know what is causing this problem (and how I can stop it happening)?

I am running the front tyre at 36psi (the recommended tyre pressure.)

The tyre fitted is a Bridgestone Battlax BT 020F (same as the OEM tyre, AFAIK)
 

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For what ever reason, I'm not able to see your photos clearly. Heavy front braking shouldn't cause the problem you describe (again, I can't see it). Cupping, yes, but not bulging.
I was surprised to read that you get 3000+ miles off of a stone. I never got more than 2,500 before cords showed through. You may want to change to either the Metz or the Avon Storm II and see what happens.
 

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That tire is just wearing out. Metzlers will last longer.
 

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2005 K1200LT
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First off don't stop using the front brake (actually you can't since you have a linked system). Agressive braking in corners will also lead to this condition. But 95% of your stopping power is in the front brakes. The PRIMARY reason for this condition is low tire pressure. BMW recommends 36 but most of us get the same thing you did so we all run 42 psi in the front. It seems to help quite quite a bit in this area (48 in the rear also).
 

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Discussion Starter #6
Thanks for the replies.

There's plenty of tread left on the tyre.

The white marks on the tyres are from dust on the garage floor. Each tread section has a marked bulge (perhaps doesn't show too well in the photos, but it's very apparent if I run my finger over it.)

I think I'll switch to a Metzler (on the front, anyway.)

The back tyre is fine - I normally reckon to get about 8000 miles (if I'm lucky) out of a back tyre (I use Michelins) on my R1100 and 12 or 13000 out of the front.

The K12 did 13000 on the last back tyre (and then it got a puncture, with still more than 3mm of tread left) but each of my front tyres (on the K12) has developed this blistering after a few thousand miles.

Braking in corners? :eek:
 

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Looks like a possible sidewall separation in the photos to me, but I've never looked at a Battle Axe up close. Tire wear looks like normal cupping aggravated by low pressure.
 

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Manuel_de_Vol said:
Now the questions (I finally managed to attach pictures ;))

Does anybody know what is causing this problem (and how I can stop it happening)?

I am running the front tyre at 36psi (the recommended tyre pressure.)

The tyre fitted is a Bridgestone Battlax BT 020F (same as the OEM tyre, AFAIK)
Your tire pressure is too low. Front should be 42, rear at 46-48.

The 'Stones will feather like that especially if you brake heavy into corners but 3500 is a little early for them to be that bad. After one set of the 020's I switched to Metzlers and was much happier.
 

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Discussion Starter #9
Thanks for the comments. - I'm well aware of the different views on tyre pressures (and see my post http://www.bmwlt.com/forums/showpost.php?p=526971&postcount=5 ) on either side of the Atlantic, but if my tyres are inflated to the pressures recommended by the manufacturer [and they are - always], how can the problem be caused by under-inflation? (Unless, of course, the manufacturer got it seriously wrong.)

It was another beautiful day here today and I had an appointment in Mittenwald followed by another in Murnau (just had to ride along some spectacular roads, with spectacular bends and scenery ;) )

There is a guy in Wallgau (en-route) who is a locally famed BMW specialist. I stopped off at his shop and talked to him about the tyre problem.

He laughed. "I can show you 3 bikes like that right here" he said. - And did.

"That's quite normal for a K12. Heavy bike, twisty local roads."

(Perhaps the tyre is inadequate?)

"Your front tyre may look funny, but it's quite safe to ride on. I see this 'problem' often and for some reason, the bumps are usually worse on the left side of the tyre."

He may well be right. Around here, people tend not to ride too quickly. - There aren't many Motorways/Interstates /Autobahnen and we do have some spectacular biking roads.

I found (with the previous tyre) that although it was OK at speeds up to about 75, the stability degrades gradually above that and at Autobahn cruising speeds, the front wheel tended to wobble a bit.

I don't ride my bikes hard. I'm quick, but there is a difference between a road and a track and I don't go on tracks very often.

I do, however, expect the performance of the bike (and particularly that of the tyres) to exceed my own capabilities.

When I was a lad, any TT racer would've given his eye teeth - nay, all of them - for tyres half as good as those on which we ride around today.

'Bobbly' tyres (like the one on the front of my K12) don't look good, don't feel good and - 'bei Näße' don't work too well, either.

I asked him what tyres he would recommend, but he didn't seem to be over-impressed with any of them.

I suggested fitting a Metzler and he said 'Nothing wrong with them ...but see what Michelin has to offer.'

I will.
 

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Try the Metz and DO try running then at 42 f / 48r... makes a world of difference.
I'm hoping to get 16-17,000km out of a single set of Metz 880's, towing a camper trailer around Aust....
I have Ultraseal in them and will maintain the higher pressure (normal pressure for me) the whole trip.
2c..... cheers
 

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Also dyna-beads eliminated most of the cupping for me with 42/48 pressure. Also Mr. Dragon mentioned quite awhile back that Ride On does about the same thing.
Speaking of....where is Dave? Haven't seen him post anything in quite awhile.
 
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