Firstly, very sorry for starting another tyre thread. Really am! But I can't find a definitive answer anywhere..

I have a 3.00x17 three spoke rear wheel which is wide enough to take a 150/70 tyre, which would give me a wide choice of very modern rubber. My K also has the later 1100 centre stand and the stock exhaust. Can anyone tell me for definite if there is enough room in there for a 150/70 to fit? I have a 130/90 in there right now (a balloony Avon Roadrider) and it is already disturbingly close to rubbing on the left foot of the centre stand, but a 150/70 would be smaller circumference so might be okay..?

If no one knows, can someone at least describe how tight the fit is with a 140/80? Is there more than 5mm either side?

Again very sorry, but at least I'm not asking what oil to use or what grease to lube splines with

I am running an Avon 140/80 17 on the rear of my K75 with standard Y spoke 2.75 wheel and there's heaps of room , at least 2-4mm clearance to the swingarm. Seriously though I have not had any sign of the tyre contacting the swingarm and have used three tyres of that size over the last 30,000km, a Pirelli, a Michelin and now the Avon, all radials.

I believe the K100 and K75 are the same dimensions in that area. I only have the standard centre stand so can't comment on whether the K1100 stand would reduce clearance on the left side. The 3 inch wheel might also change things from my setup.

I seem to recall one of the guys here in Oz has used a Bridgestone 150/70 rear on a K100 but not sure on what wheel.

Hope this info is of some interest.

Cheers

Posts I've saved from the Net say the 150/70-18 will fit the 4.5x18 three-spoke, and a 150/70-17 will fit the 3.00 x 17 three spoke from a K1100LT, and all the way up to a 160/60-17.  Personally not sure that a 140/80 can get shoehorned in there.

Sources:
http://www.bmbikes.org.uk/Forum/viewtopic.php?f=13&t=14728
https://www.k100-forum.com/t1556-k1100rs-rear-wheel-fits-k100k75-uk

I did manage to determine that a 150/70 will physically fit the standard wheel on the K100 8 valve with the just about bare minimum of clearance to the K100 stand and Monolever swing arm but.....

1: I like Bridgestone BT45 and it doesn't come in that size.
2: There are reservations about the wheel being too narrow for the 150 width.

How did you determine that, Olaf? Words on the internet or real life experience?

It is a definite that a 150/70-17 tyre can be fitted on a 3.00x17 rim, that's no problem. Also for definite is that a 140/80 fits a standard K100 8v with the original style stand (I believe?? Why else would the manual say it's ok?). The 1100 stand gives you slightly more room, room that could maybe be filled with tyre..

I have read a few threads where people squeeze in 160/60-17 tyres but I am not so bothered that I would go to the lengths they have - grinding the stand back, welding up the hole, and then shaving the strengthening rib off the swingarm. That is crazy. But if the tyre were a mere 150/70, would it be so bad.. I could also possibly use an extra spacer between the wheel and the hub to move the wheel away from the swingarm a bit, and make use of the extra space provided by the 1100 stand. But by then we are talking mere millimetres..

I refuse to believe this hasn't been done before, someone must know!

Snod Blatter wrote:How did you determine that, Olaf? Words on the internet or real life experience?

It is a definite that a 150/70-17 tyre can be fitted on a 3.00x17 rim, that's no problem. Also for definite is that a 140/80 fits a standard K100 8v with the original style stand (I believe?? Why else would the manual say it's ok?). The 1100 stand gives you slightly more room, room that could maybe be filled with tyre..

I have read a few threads where people squeeze in 160/60-17 tyres but I am not so bothered that I would go to the lengths they have - grinding the stand back, welding up the hole, and then shaving the strengthening rib off the swingarm. That is crazy. But if the tyre were a mere 150/70, would it be so bad.. I could also possibly use an extra spacer between the wheel and the hub to move the wheel away from the swingarm a bit, and make use of the extra space provided by the 1100 stand. But by then we are talking mere millimetres..

I refuse to believe this hasn't been done before, someone must know!

Yes I've fitted that tyre on the 3" three spoke rim on my K1100 and it works well, I've also put that tyre and rim on my K100rs 8v without any problems, I do have the K1100 stand on the 8v rs.
There is still about 5mm clearance at the swing arm.
The ideal three spoke rim for the 8v would be the 3" B rim from the K75s as the A rim from the K1100 has an off set.

Thank you smithy!

How do I know the difference between the A and B rims? I didn't buy the wheels, they came on the bike, so no idea what they were sold as..

Snod Blatter wrote:Thank you smithy!

How do I know the difference between the A and B rims? I didn't buy the wheels, they came on the bike, so no idea what they were sold as..

Check the inside casting of the spoke on the rim, a type A is K1100 type B K75s

Turns out I have an "A" rim. On the one hand this is good because it means it definitely will fit, as per your experience. But on the other hand it's annoying that it's not quite right.

I have used it before and it seemed just fine though. Sorry for what is probably a silly question but google is not helping me much, what is the offset and which way is it? Would a B rim give any more room either way? Not that I'm going to search one out if this A rim fits just fine

As far as I know the type A rim is designed to fit the parra lever and the type B to fit the mono lever, therefore the type B should line up perfectly with the 8v set up. I cant tell you how far out of line the type A is on the mono lever set up as I never measured the track when I fitted that rim on the rs, and now I've swapped the 150/70 T30 tyre from the three spoke rim onto the Y spoke just for fun, and so far it's going okay, time will tell.

Note I'm not suggesting anyone should do this, I've just got the spare tyre and rim and thought I would give it a go.

 

I'm surprised by how little ballooning is happening there, since everyone seems to recommend a 3.50 rim for 150/70 at the very least. How difficult was it to get on to the wheel?

Given the Y spoke will have the correct offset, do you have anything with the monolever setup to see if it still fits?

Anyway, I will come back to this thread to update on whether it really does fit or not and how much room is left either side. First I have to get it through an MOT (roadworthiness test) with the old Roadrider on the back as mixing bias ply and radial should technically be a fail, and of course wear the last of Roadrider away. But I will be back, promise!

The A type wheel will offset 14mm to the left on a monolever rear drive.

Phwoar, that's quite a bit. I was happier not knowing that.. Wonder if anyone has a paralever setup I can have for a fiver? Ah but I need a shock too. I might be able to stretch to £10 for the lot.

Anyone?

Snod Blatter wrote:How did you determine that, Olaf? Words on the internet or real life experience?

It is a definite that a 150/70-17 tyre can be fitted on a 3.00x17 rim, that's no problem. Also for definite is that a 140/80 fits a standard K100 8v with the original style stand (I believe?? Why else would the manual say it's ok?). The 1100 stand gives you slightly more room, room that could maybe be filled with tyre..

I have read a few threads where people squeeze in 160/60-17 tyres but I am not so bothered that I would go to the lengths they have - grinding the stand back, welding up the hole, and then shaving the strengthening rib off the swingarm. That is crazy. But if the tyre were a mere 150/70, would it be so bad.. I could also possibly use an extra spacer between the wheel and the hub to move the wheel away from the swingarm a bit, and make use of the extra space provided by the 1100 stand. But by then we are talking mere millimetres..

I refuse to believe this hasn't been done before, someone must know!

Been off with 88 for a few days, only now seeing the posts.

I fitted the BT45 140/80 on the K100, its on original Y spoke wheel and it has the original K100 centre stand. I have been using this size for a few years. I still have 6 mm between the tyre and the swing arm, a 150 tyre will be 5mm wider each side but the narrow profile of the wheel may possibly cause this to be slightly less if it is narrower than desirable for a 150mm tyre. We had a little rain at the weekend and as usual the tyres felt very planted in the wet.

I haven't fitted the K1100 centre stand so I cant comment on if the 150 wide tyre will fit. Personally I wouldn't go grinding stands to make them fit.

Snoddy some 150s will fit some don't fit there are small differences in the width from brand to brand. I seem to recall that one of the forum members fitted a Pirelli sports demon but the usual disclaimer applies ie if it don't fit don't have a fit.

I understand that some tyres are narrower than others, I will try and pick one without a "rib" on the outer edges or anything like that.

I wasd at a bike show on Sunday and came across a K100 that had been cut down a bit, so you could see right into the swingarm area. It had a 130/90 Avon Roadrider fitted to the normal Y spokes, and by golly it was very nearly rubbing. So I guess the 140/80s only fit because they aren't quite so large in circumference, so sit within a slightly wider space?

If all else fails you can still get Tourances in 140/80

Oh by the way, if it comes to it, can I leave out the spacer between the wheel and the hub? Or is that a terrible idea? Does it work like a washer, to stop rubbing or brinelling, or is it just a spacer?

I have never come across an explanation for the spacer and every K I have worked on has had a spacer the same size yet there are 2mm and 3mm listed so Hoonose. If you left it out the wheel will sit closer to the swingarm.

The only use I found for that spacer was to reduce the diameter and fit it between the disc and the bevel drive rather than between the disc and the wheel.

Oh alright - I was fitting a cast-iron rear disc and the damn thing was binding against the side of the caliper. Switching the (reduced diameter) spacer to the inside of the disc and then spacing the caliper out (towards the wheel) lined everything up perfectly. So it does have a use (sort of).

To bring some closure to this thread in case anyone was wondering what happened, the bike failed its MOT because the rear Avon Roadrider had cracked badly in the centre and was showing cords. This meant I had to replace it with another bias ply in order to obtain a year's MOT, so I'm on a 130/90 Metzeler Sportec Klassik for the next 6000 miles or whatever it lasts for. If anyone runs a 150/70 feel free to post your results here, preferably with pictures and overblown metaphors for how close the tyre is to rubbing on everything.

So, the Klassik eh? Seen a lot of talk about it but no one has ever tried one, ever ever. I like it. It has a hard compound and very stiff construction, very old-fashioned Metzeler but it is nicely curved and seems to really bite into the road if you give it something to deal with. It also gets really warm, as most modern tyres seem to. I have ridden in the rain and it's a bit squirmy but not frightening, this is surely down to its stiff construction and the way it doesn't mould into the road. The ride is also a bit harsh, again it's built to be stiff but that does mean it keeps the bike under control in the corners, not a lot of sidewall flex happens so not a lot of weaving and wallowing. But that may change with miles..

Mostly though it's called Klassik.

10/10.

Don't think I would be liking a tyre that feels squirmy in the rain.

I like my BT45 and the very planted feel in the rain, couldn't give that up.

I've got Bridgestone T30's on my Y spoke rims, the rear is 150/70 and I have put over 7000 km on them now , in all conditions with no problems.