Looking for suggestions for new tires for my 85 K100RT. What has worked for good handling wear etc.

Although the standard size for the K100 is front 100/90-18 and back 130/90-17 you can easily go up a size to 110/80 and 140/80 respectively without any problems. This will change the cornering characteristics and give you a slightly larger contact patch which will feel more 'planted'. Also, the larger tyres will be slightly less inclined to be bothered by cracks, gaps, lines and other irregularities on the road.
Unfortunately, the only sport touring tyres available in the sizes above for the K100 with the Y-spoke (snowflake) 2.75" rear wheel are bias ply. Some single compound and others dual compound.

Bridgestone BT45 is a very popular tyre for the K and for a bias-ply they perform reasonably well to a point. The front tends to scollop as they wear due to the block tread pattern, which is probably their biggest failing.

The Metzler Lasertec has been the worst tyre I've used and only managed 10,000km out of the rear.

Back when they were available, the Avon Azaro45 radial was pretty awesome and I managed to get over 16,000km. A radial will transform your K to a mean cornering machine. This has been discontinued in the 140/80 as was the Battlax-023 radial I had on the front.

The best bias ply tyre available for the K100 imo is the Pirelli Sport Demon. They are a single compound construction but they are sticky and I've ridden quite a few wet klms on these with no problem. I've had over 13,000km out of this tyre.

Some on this forum have stepped it up a notch and fitted 150/70-17 to the rear. This is a little oversize for the 2.75" rim, so fit these at your own risk... but by going to a 150/70 you can find a radial like the Battlax T-30 or the Pirelli Angel GT. I've not tried this on my K100 yet but others may tell you of their experiences.

There are also other options in 'adventure' tyres, including radials as well as some good dual sport tyres.

As Holister has mentioned there are some radial tyre options for our K100 and K75 wheels in the dual sport ranges.

I have run 3 different manufacturer 140/80 x R17 radial dual sports over the last 35,000kms on my K75 which has the standard Y spoke 2.75 inch rear wheel.

These have been a Pirelli, a Michelin and currently an Avon. Unless you are doing track days on your K bike I believe these tyres are well up to the demands of every day riders so well worth a look. The large capacity Adventure type bikes that these tyres are designed for are fast good handling machines and a high proportion of them rarely see a dirt track.

Just a comment on the common terms used to describe BMW cast alloy wheels. I believe the term "Snowflake Wheel" is used to describe the first generation of alloy wheels used on airhead boxers as seen in the photo below.



Whereas the term "Y Spoke" is used to describe the wheels on the K100 and K75 bikes in the 1980s, as shown below.



Which were followed by the "3 Spoke" range on the later classic K bikes.

Thanks for your wonderful feedback, I am mainly looking for a tire that will give me good handling characteristics, going up a size sounds like a good option. I was already considering the Pirelli so I may go with that suggestion.
Thanks again for your feedback

I have been using the Bridgestone Battlax BT45 for 6 years now. All Y spoke wheels.

I have tried 100/90 and 110/80 and 110/90 on front and prefer the 110/90 of all the sizes. The scalloping has occurred but over quite a few of them I have worked out that the main culprit is tyre pressure. I have found that I have to keep 38psi in it no matter what and I have now got 2 consecutive ones to have no scalloping at all running at 39-40psi in all conditions and it feels like running on rails.

Rear I have used 130/90 and 140/80 and much prefer the 140/80, usually running 42psi and higher at 45psi when loaded down with camping gear. After my last new rear I am planning to try a 150/70 rear to see how I get on with it as there appears to be enough space between the 140/80 and the swing arm to allow a fit.

I use the K all year and find a huge confidence in them in the wet and especially cold wet weather, much more than in the car! A wet day on the K on curvy roads is fabulous on them. Recently replaced rear pads and the back end feels totally usable in wettest of conditions. I get great mileage too, rears have been giving me 10,000 miles. Looked at the rear last week after 6,000 miles and still looks

I did have Lasterecs on both the LT and RT when I got them and they were awful things. No idea what mileage they were doing but zero confidence and so easy to get the to slip. I cold weather they would not warm up at all, despite not being old tyres.

I don't consider mileage at all when I get tyres for bikes, confidence is what I look for but the Battlax covers both well. I take the K down to my local Honda dealer and his ride in tyre service is €30 for fitting the two tyres while I drink his coffee. His mechanic there was a K owner too. Can't argue with that and never harms to have someone else's trained eye over your bike. Last time my brake pads friction material parted company with the backing plate and he supplied and fitted 2 sets of front pads for €40!.

But there are others too. 88 rides all round in similar conditions to me but uses a different tyre and is also very happy with them.

Very useful info!  Thanks!

Just bolted a set of BT45s onto my '85 K100RT yesterday and looking forward to trying them out!

Nick Knobil
Bowdoinham, Maine USA

I just ate through a rear tyre. Was an Avon road rider 140. While fine, it did everything I wanted, it only lasted ~2000mil.

So now I just plonked the cheapest I could find on. Which was this:
http://www.moto-tyres.co.uk/cgi-bin/rshop.pl?s_p=Maxxis-M6103-130_90-17-TL-68H-Rear-wheel&details=Ordern&typ=R-268154&cart_id=65480418.1110.31826&ranzahl=1&Breite=130&Quer=90&Felge=17&weiter=0&Ang_pro_Seite=10&dsco=1110&m_s=1&rsmFahrzeugart=MO

No complaints but not ridden in the wet yet and doubt I will much. Price is hard to beat anyway

Radial.

Not sure on the size-wise rear for Y-spoke but 110/80-18 for the front.

Johnser wrote:I just ate through a rear tyre. Was an Avon road rider 140. While fine, it did everything I wanted, it only lasted ~2000mil.

How did you do that? Mine lasted ~5500 miles and there was still a bit left to go, but I had to stop using it as it was tearing apart in the middle. I ran it at 42-46PSI, sometimes 48, the more I put in it the better (less wobbly) it felt.

Snod Blatter wrote:

Johnser wrote:I just ate through a rear tyre. Was an Avon road rider 140. While fine, it did everything I wanted, it only lasted ~2000mil.

How did you do that? Mine lasted ~5500 miles and there was still a bit left to go, but I had to stop using it as it was tearing apart in the middle. I ran it at 42-46PSI, sometimes 48, the more I put in it the better (less wobbly) it felt.

I just checked, it was actually ~2500mi. Dunno, heavy bike and a heavy right hand I guess. I was also running just over 40psi. Probably because I hadn't taken it on any longer trips on that tyre, short rides where time is of the essence usually in heavy traffic is less kind than longer, chilled out cruises.

My point being, £50 for a rear that fits is too cheap to be picky over. Seems to hold on out of corners alright and like I said I mostly ride in the dry.

Not sure I'd go quite so budget on the front though. Bit of rear slippage is much more acceptable than the front

I know the Cornish roads can be a bit rough but... 2500 miles! I usually see at least 5000 on mine running at 38psi and Irish roads are worse than Cornish ones! Admittedly, that means LFB doesn't get a huge amount of right hand. Too much trying to get to Jamaica Inn before closing, that's what it is. There's better pubs in Wadebridge mind!

Some of the back roads are a bit scruffy but most of the A roads are pretty decent. If a little (lot) congested. I'm much further north than those places, while a few local pub trips do happen, I'll bet that a good portion has been smeared off on the a30, popping down to the south coast of Devon.

Any heavy acceleration or fast cruising on these 1/4ton aluminium cuboids is going to be tough on a relatively skinny back tyre. The higher pressure than most probably doesn't help the centre of the tread either.

I just hope I can get another £50 replacement next time

Snod Blatter wrote:

Johnser wrote:I just ate through a rear tyre. Was an Avon road rider 140. While fine, it did everything I wanted, it only lasted ~2000mil.

How did you do that? Mine lasted ~5500 miles and there was still a bit left to go, but I had to stop using it as it was tearing apart in the middle. I ran it at 42-46PSI, sometimes 48, the more I put in it the better (less wobbly) it felt.

I think most tyres are rated at a max 44psi. Its usually stamped on the tyre wall.
Apart from accelerated wear, higher pressures will also cause the tyre to overheat creating other problems. 48psi sounds a bit extreme, maybe you meant to type 38?

I recently rode half way around Australia from Perth WA to Brisbane QLD and back down the Sydney... about 8000km. I started on a half worn out tyre and by the time I got home the side treads were totally gone. That was a PR2.

The most I've got out of a tyre was 16000km rear and 28000km front. They were radials. I'm not happy if I get less than 12k. I don't use my brakes much and try to accelerate back up to speed as I come out of a corner and that's around town as well. It's all about preserving the centre of the tyre.

The BT45 on the K are near their weight limits anyway, so near max pressure is probably needed. I found that under 42 psi rear gets hot and wallows a bit. As miles builds it does tend to square off. Presently have about 6,500 on the rear and it looks good for another 2-3,000 miles. Will change both, same as last time.

Rear shock is a YSS and is excellent and been enjoying some spirited riding with camping gear on and only small amount of preload as in about 30%. the replacement shock seems to be helping rear tyre life too.

Holister wrote:I think most tyres are rated at a max 44psi. Its usually stamped on the tyre wall.
Apart from accelerated wear, higher pressures will also cause the tyre to overheat creating other problems. 48psi sounds a bit extreme, maybe you meant to type 38?

Nope, 48. Below 42 it felt very wobbly indeed, as did the Conti Go before it (which also did around 5500 miles). I have a Metzeler Sportec Klassik on the back now and the stiffer construction is really helping, 42PSI seems fine maybe even a little hard. Too early to say how it is wearing though, only managed 500 miles on it so far.

I have a Michelin Pilot Activ on the front and have been very pleased with the grip and comfort it has provided, it almost feels like a radial to me. The only thing I don't like about it is the combination of me and bike puts it very close to its maximum rated load, and it does have a lot of small tears in the middle though they don't go very deep. I wonder how well it will cope when it gets worn down a bit. 38 PSI goes in that, or thereabouts.

I have set up an ebay search for a shock, my standard thing seems very soft and I'm sure it was weeping before the weather warmed up. It could well be the source of my wobbling woes!

Snod Blatter wrote:I have set up an ebay search for a shock, my standard thing seems very soft and I'm sure it was weeping before the weather warmed up. It could well be the source of my wobbling woes!

It's definately the source of your wobbling woes. How about buying a RamShok?

Dai wrote:It's definately the source of your wobbling woes. How about buying a RamShok?

The money? I know they're good for the price but daaaamn. Plus the bike isn't quite on its knees yet so there's still more mileage in it

When I got LFB I hated the bloody thing. It handled like I was riding on cowshit on ice. I fitted progressive springs at the front and a RamShok at the rear - it was like someone had given me a brand-new bike with all of the old scratches in the paintwork. That was a total of approx £400 more than just well-spent. I went from hating corners to scraping me boots

And if somebody says 'and falling off' I'll poke their eyes out

Mine already has progressive (Progressive?) springs in the front, but it also has S forks and I somehow don't think the two make a good pair. The receipt I have doesn't specify if they were specifically for S forks or not, and I wonder if it doesn't sag enough at the front. Coupled with the saggy rear it may explain the strange handling.

I may put some effort into it in the future, the forks are shot with scored stanchions and big leaks so I'd like to replace them with the later Showa forks off a K75, possibly with cartridge emulators. And sort the rear too with whatever I can find.

I can't imagine scraping my boots, it looks like I'd run out of front tyre before that happens! There's already bugger all chicken strip left, a frightening prospect.

For rear shocks do check out he YSS shocks. So far seem good for the money.

Best deals were on eBay.de, the ones on eBay.co.uk were much more expensive.