Hi , I recently bought my 1986 k100rt around christmas, since then using your forum I,ve been able to service and change quite a few rubber parts which were perished . I like messing about and generally fettling with the bike .
However I,ve been riding around for three months on tyres that do not match the chart under the seat. The tyres are metzler lazertec which are recommended but the size of the tyres are different .
The tyres on my bike are , front 110-80, rear 140-80 . The chart size says , front 100-90, rear 130-90.
Can anyone see a problem?

G'day Joinyman , you will find that most here are running that size on their standard rims ( 110/140 ) it's what I'm using at the moment & have been for many years , no problems

JR

Melbourne Australia

Thanks mate, the handling has always felt ok ,but its nice to know someone else has the same tyres!

Your Avatar picture looks like the bike has 3 spoke wheels which are from a later bike and fit different tyres.

bikerboy wrote:Your Avatar picture looks like the bike has 3 spoke wheels which are from a later bike and fit different tyres.

Thanks for the idea , but they are in four symetrical Y sections.

I am running 100/90 & 130/90. I think these are the standard but Klompy recommended I go up a size. Is there a way of getting a wider tyre on the rear? If so how wide can it be?

Brand is also important to consider. Metzler's and Avon's IMO are highway tires, very stable and long-lasting but limited to 100/90 in front due to handling.
Just put new Bridgestone's on my '85 RT; a V-rated 110/90 in front and H-rated 130/90 in the rear. These are performance tires for improved handling at such speeds as allowed here in the USA.

we call those sizes plus 1's bigsax (meaning next size up )

i dont think there are many more sizes ..."commonly available " that suit the tyre build (crossply - redial ) and the rim sizes commonly used .

it seems to me that the extra size gives a bit more wear out of the life of the tyre and slightly more tyre on the road

my plus 1 front pirelli lasted me well over 20,000 ks and still had life, till i hit something on the road and put a nice juicy cut accross the tyre that i didnt feel comfortable with . so i changed it

Did you mean me Bikerboy ? , I've got 3 spoke wheels from other models yes , rim width is 2.5 inch up front and 3.0 inch in the rear instead of the 2.75 inch Y spoke , same deal , before I changed the rear rim I still ran a 140/80/17 , hope that clear's things up ( 160/60/18 upgrade is being worked out now , I have the rim & tyre , just working out where to grind away )

JR

Melbourne Australia

JR_K100RS wrote:Did you mean me Bikerboy ? , I've got 3 spoke wheels from other models yes , rim width is 2.5 inch up front and 3.0 inch in the rear instead of the 2.75 inch Y spoke , same deal , before I changed the rear rim I still ran a 140/80/17 , hope that clear's things up ( 160/60/18 upgrade is being worked out now , I have the rim & tyre , just working out where to grind away )

JR

Melbourne Australia

JR, I think I have the same wheels as you. Could you post when you have worked out the best combo please. My tyres are good for another couple of years with the klm I do but it would be good to be prepared.

I bought new Michelin Pilot Active tyres in standard size's to my K. Will report how they perform when my season starts. As new they seem to have 6mm (rear) and 5mm (front) track. I suppose they should serve me for whole season (7000 - 12 000km), but we shall see.

Update: They are not that good, or 2,3/2,6 bar pressures were too low. Front has about 2mm left and rear is gone and I got little more than 8000km with them.

G'day Bigsax , currently I'm running 3 spoke wheels , the front is from a K75S and is 2.5x18 the rear is from a K1100LT and is 3.00x17 , I plan to keep the front but replace the rear rim with a 4.5x18 which will let me run a 160/60/18 true radial together with a 110/80/18 up front , I've got the rear rim now and am working through the best way to fit it up , what I'm doing is by no means new , take a look at Two Wheels Better's write up on "wide wheels for a K100" , very detailed , also Charlie99 , they have both completed the mod with great results .

I will certainly be posting ( with pics ) when mine is finished

Hope this helps


JR

Melbourne Australia

I meant Joinyman when I mentioned 3 spokes.
My bike has the 3 spokes with the 160 rear. I recently bought a pair of tyres, secondhand, Michelin Pilot road 3. They were less than 200 kms old and came on a set of 3 spoke wheels that are the same as my bike. I now have a spare set of wheels for a 16 valve K100RS should there be anyone in France who needs them.