G'day all, I'm new to the K100 / bmw bikes, well, had it a year now....I'm due for a new set of tyres on my '88 k100RT, the tyres on it when I picked it up are Michelin Macadams. I too get the wiggles over line markings with them. But for mileage, I've got 21,000klm out of the rear, which aint bad at all. At the risk of opening up a can of worms, anyone got some good tyre recommendations, that have better feel, but could do those Klm's? I travel to work most days, via freeway driving, 180klm round trip. Any comments on Continental TKV 11/12, Metzeler Marathons 88 or Dunlop 205's (only others I've looked at so far)
cheers,
Andy.

Siegfried the K-BIKE (that is his rego) has Michelin 2CT Pilot Road on the front and Metzeler Roadtec Z6 on the back I will probably go for Pilot Road 2CT front and back when the Metzeler wears out I like the feeling of safety and grip I get on the front wheel so I am looking forward to both.
Regards,
K-BIKE

Hi K-Bike, going to try a set of Continental TKV11 front / TKV12 Rear. see how they go. From your experience, what tryes pressures have you been using for 1 up? The manual figures for 1 up seem too low to me.....I tend to run 38psi front, 41psi rear.

Hi,
I asked Michelin direct telling them what the bike was and the tyre size and this was their response:- "The pressures that we would recommend for your bike are - Front 32 psi / Rear 36 psi"

Regards,
K-BIKE

Hi guys

I have recently put on Bridgestone Spitfires front & Rear. Pressures recommended from manufacturer for 1986 K100RS were 33 & 36 psi.

Mal

Hi K Bike, the Continentals are on, done almost 1000 k's on them so far (180 klm round trip to work!) seem very stable so far, but I do get a noticeable bar shake around 60klm if I take pressure off the bars....but I had this with old tyres also, thats why I thought higher pressure on the front may help. bike has new headstem bearings (11 mths old), which dont seem too tight. Any ideas on the bar shake, or is it a 'K' thing? cheers Andyb.

Hi Andy,

Not sure about the bar shake thing as mine is running Macadems and the wheels aren't in the best shape (literally) but my bike is rock solid at any speed.
I am pretty casual about tyre pressures too (read lazy) but they are in the range mentioned by K-bike.
The only thing I have read about shake in the bars is to do with the headstem bearings being too tight but that is more of a slow weave than a shake.

FWIW.

Regards,

Phil M

Hi Andy,
Just check your steering head bearings are properly adjusted and also that the fork legs are correctly lined up. Also check that there is nothing odd about the alignment of the rear wheel, should not happen in a shaft drive but since new who knows what has happened or been done to it (unless you owned it from new)

Last thought just check the beads are evenly seated on both rims.
Regards,
K-BIKE

Did you have you wheel balanced when you replaced the tire? In some shops, they replace the tire but balancing is optional. An unbalanced front tire will generate a bar shake at this speed. I had the problem before (On a Suzuki GT 750). At the time I had checked everything else too but it was as simple as couple of grams of weight.

There is a dot marked on the tire. What is that? When they manufacture the tire, They insert an extra piece of rubber in the tire to compensate for the weight of the valve stem. The dot is to indicate the position of this extra weight.
I don't remember if when the tire is installed, the dot should be at the opposite of the valve stem or at the stem. A saw a lot of mechanics not paying attention to this.

Here is a good page explaining the wear pattern on a front tire:Tire cupping on a BMW

Bert

G'day all, Neither tyre has any weights on them, tyre fitter said the back was almost spot on, and that the front was only around 5 grams, so he reckoned it didnt require it. Maybe I should take it back in and get them done anyway. I will check the position of the weight dot, to see if its opposite the valve. Possibly get the headstem re-checked. Is there any 'easy' way to get at them?? (havent checked the manual). Back wheel should be OK, I replaced the rear diff unit myself recently, all parts seemed to marry up fine, and no movement apparent in the swing arm bearings. Cheers Andyb

Hi Andy,
Sorry but your mechanic is Full of Fertiliser to be polite. Your wheels need to be perfectly balanced otherwise when you are hammering along at speed, especially if you are in ACT with no speed limit, the 5 grammes becomes a big weight and it is stressing wheel bearings and head bearings plus making you less stable.

Anything that makes you less stable is as they say A BAD THING! sorry for shouting but anything which reduces your stability increases your level of risk.

Imagine you are leaned over close to the limit of adhesion (perhaps you misjudged a corner or it tightens up or you need to change your line due to an object in the road) then having the tyre oscillating at some resonant speed could be just the thing to cause the tyre to go outside the grip envelope and unless you are a magic rider you are going down.

Sorry to be so dogmatic and pedantic but your mechanic is increasing your risk and that ticks me off, we cannot afford to lose you or your bike both are precious to us all we are a band of brothers united by our love of the mighty K.
Regards,
K-BIKE

Thanks for the reply K-Bike, tend to agree with you. Never had this problem before, and havent ridden another boomer to see how mine compares......so I think its back to get weights on, I come in to work via freeway at 120+ for 180 klms every day, so its gonna make a difference, quickly to my machine. I'll let you know how it goes....Very happy with the continentals so far... cheers Andyb

Good on you Andy,
I remember when I had a Gold Wing I thought my tire balance was OK and a friend said when you are doing 70 + mph stand up and sight down the fork legs like a rifle barrel. I did (it is not as dangerous as it sounds on a bike as large and stable as a Wing) and I could see the forks oscillating back and forth what looked like 3/4 of an inch. I balanced the wheels and repeated the test and the tubes were absolutely stable.
Regards,
K-BIKE

Here is a dynamic way to balance a tire.
I have friends using the dyna beads and they are please with the result.



Here is how to balance a wheel with weights.

Well, after quite some time, all problems after i replaced Tyres have been sorted. Front wheel fitted with Continental TKV11, balanced and all good. Now the rear was a different story.....Turns out the rim had a buckle and a slight ripple in the lip. tried to get it fixed but they could only re reoll the lip, and not fix the buckle. So I had to track down a replacement rim. When they fitted the COntinental TKV12 onto the new rim, the tyre was still out! I dont know if it had formed a 'memory' from the buckled rim, but it was a nightmare to ride on. So they ordered a new rear tyre and replaced it, all free of charge, and now the bike is beaut! So much better to ride, no more bucking and squirming on corners, and the reduction in vibration has been amazing. With summer just about to hit, my confidence in the old girl has been restored!
Thanks all for your tips.......AndyB

GREAT NEWS!!!!
Regards,
K-BIKE

As I had said: "as simple as adding few grams of weights"

We are all guilty not to start looking at the most obvious when we have a problem.

Enjoy your new balanced tire!