Ned, I agree...it is v.subjective and scraping the footpegs is not my cup of tea these days. But, white knuckle moments do occur when you least expect, and tyres are probably the most critical thing between surviving or a don't-even-think-about-it event.

CHeers, UG.

Do any of you use later model wheels on your early series K bike which would allow you to use radial Pilot Road 2 and other brand dual-compound tyres? I believe you cannot get them to fit our early series 'skinny' non-radial wheels. They appear to be available in the narrowest sizes of 150/70 rear and possibly a 110/80 front at best. Same thing goes for the Metzeler Z6, Conti Road Attack, Dunlop Road Smart, Pirelli Angel ST and most other, if not all of the newer dual-compound tyres that are much-hyped, but quite effective, these days. We are, sadly, limited to the more basic sorts of bias belted (non-dual compound) tyres, if we have the stock wheels of an early K bike. But the '90s era K's with a 120/70ZR17 front and a 160/60ZR18 rear tyre can use them.

I like the Pirelli Sport Demon bias belted simply because they stick in all weather, handle with aplomb (lightening the steering feel considerably), are readily available at a fair price, and last a decent amount of time on the slightly overweight K100RS, as compared to other brands I've used and sold over the years.

I have just fitted(last week) a 18x 4.5 from a k1100rs with a metzler mez4 in160/60/18 on my 1986 abs K100rs, I had to remove the caliper, as the tyre is a bit of a squeeze to get in, fits without touching anything........until you take it off of the centerstand, the left leg hits the tyre-so i used the angle grinder to it until I can find a K1100 center stand.
The main diffrence is that even with a well worn rear tyre it wont wobble over whie lines and crappy roads like the old rear(130/90/17) would even with a new tyre.
Ray

A coupla months back on eBay in the US there was a bloke selling off a widened wheel (by Kosman Racing) that was the traditional 'Y' spoke which had additional width welded into either side. It would've taken a 160mm-17" series tyre and also on offer was a sidestand assembly that'd been modified to clear. It got flogged for about US$200.00 in the end.

Dunlop's Road Smart is available in a 110/80ZR18 size for the front and with your mod or a Kosman, etc. we could be in on the new types of rubber available. Another option is the 3" wide three-spoke wheel from a K1100 in a 17" hoop that could just about squeeze a 150/70ZR17 tyre on without too much change in the tyre's profile. That'd just about clear the stand and swingarm and be closer to a modern size without much grinding, cutting and other modification.

A few years back I owned a sweet little R1150R. It came with the 170/60ZR17 tyre and slightly narrower wheel. I was working in BMW spares at the time and so I popped for the 180/55ZR17 tyre and the slightly wider wheel. 'Everyone' said it would slow the handling down a bit until I reminded them that that was an option on the K1200RS and the R1100S at the time and look what it did for them. The chorus died down. It made no difference to handling, and I was open to a wider choice of soft and medium compounds for track days and sporting riding, which was my goal. Score! I wish I didn't sell that undersung bike. Nowadays even the nimble little F800 series street bikes come with a 180mm rear tyre.

Sometimes the mind works hard on solving problems over a coldie or a hot cuppa!

Good question TWB.

In radials, the answer is yes for the front, but for rear, it is difficult to find any radials that will fit except for Avon Azaro, if you can find it. It appears that most radials skip the 140/80 and start at 150/80.

Front... well yes and no. Azaro ZR doesn't have the front to fit but its close cousin Storm 2 ZR has a correct size. In short you can you can find a bunch of radials that will fit the front, including Pilot Road 2.
here is the size selection for Pilot Road2:

FRONT
110/70 ZR 17 (54W)
110/80 ZR 18 (58W)
120/60 ZR 17 (55W)
120/70 ZR 17 (58W)
120/70 ZR 18 (59W)

REAR
150/70 ZR 17 (69W)?
160/60 ZR 17 (69W)
160/60 ZR 18 (70W)
170/60 ZR 17 (72W)
180/55 ZR 17 (73W)
190/50 ZR 17 (73W)

Rear is the problem; it starts from 150 I wonder if we can squeeze 150 on K100 rim? It would make our selection easier. Now I have to have Azaro on the rear and Pilot Road2 on the front.

I feel that it would be possible to fit 150 in the space with a little persuasion, but 150 may not be safe on the rim ... it is just one size too big.

I am not looking to do this for cosmetic reasons... it would be nice to go to the store and get a set or modern radials for around $350 vs $420 if you buy them indiviadually. On top of that you would have a matched set of radials for all the good reasions.

A 150/70ZR17 will not fit and should not be fitted to the 2.75" wide rear wheel on early K bikes. The 140/80VB17 that I use IS the oversize size. You need at least a 4" wide wheel and my suggestion about squeezing one onto the 3" K1100 wheel is partly in jest and in eagerness to find a way. Keep in mind that all of the big tyre manufacturers like Metzeler, Bridgestone, Michelin, Dunlop & Pirelli make a street radial in a 150/70ZR17 - dunno about Avon as I have a mild historical aversion to them, so I don't consider them and perhaps I should once again. I've sold heaps of the other brands over the years for people wanting a street tyre for the back of their big GS for touring. Another thing for me is that I never ever mix brands. The same manufacturer goes on the front and the rear. There are too many profile design differences and compound issues between manufacturers for a start. Also, the only bike I know of that ever had a radial and a bias belted fitted from the factory was the Airhead R100GS Paralever with a radial on the back and a bias on the front. No one made a 21" radial at the time. I think the three spoke 18" wheel recommendation is the best one I've heard so far to solve our slight dilemma since it's an easy fit and the rolling radius will be just about the same.

[quote="Two Wheels Better"]

A 150/70ZR17 will not fit and should not be fitted to the 2.75" wide rear wheel on early K bikes. The 140/80VB17 that I use IS the oversize size. ...

When I started this process, from a point ignorance, I thought that radial was the norm. I only needed one tyre at the time so the Azaro was fitted and it went well. It is a 140/80ZR.

.... I've sold heaps of the other brands over the years for people wanting a street tyre for the back of their big GS for touring. Another thing for me is that I never ever mix brands.

I see, but if you want radials... then there is no choice. Maybe I should just go with the flow and fit what is available and matching... in my case I made a mistake of not researching the size issues sufficiently and now I am stuck with a radial on the back with a soon to be replaced Lasertech on the front.

... the only bike I know of that ever had a radial and a bias belted fitted from the factory was the Airhead R100GS Paralever with a radial on the back and a bias on the front. No one made a 21" radial at the time.

So it is possible. That makes me feel better because if BMW can mix play and radial, I am sure that the lesser sin of mixing manufacturers is fine provided one stays within the bounds of the tyre type. What i am saying is e.g. is do not mix slicks and sport tourer. I take your point about profiles and compunds... they need to be matched.

I think the three spoke 18" wheel recommendation is the best one I've heard so far to solve our slight dilemma since it's an easy fit and the rolling radius will be just about the same.

Not sure what that means. what is the difference between three spoke and snowflake?

See ssray's post above - he fit the later model K1100 (Paralever final drive-type) three-spoke 18" wheel to his '86 K100 and with slight mods to the centre stand can use a 160/60ZR18 radial tyre out the back. That's my plan now too!

If you're gunna fit radials and bias belted to your bike then do what you did, apparently, and be sure that the radial is on the rear only!

But onto wheel types and what they're commonly known as so as to clarify their names:

http://www.realoem.com/bmw/showparts.do?model=0312&mospid=47873&btnr=36_0158&hg=36&fg=10
This would be what we came to know over time as a 'Snowflake' and they were fitted to '78 through '84 Airheads and will fit earlier year Airheads with the 17mm front axle diametre too.

http://www.realoem.com/bmw/showparts.do?model=0503&mospid=47865&btnr=36_0164&hg=36&fg=10
This would be a 'Y' spoke and they were fitted to '85 on Airheads and early K bikes. Some people do refer to this wheel as a snowflake also but it just confuses the issue. The cogniscenti call it a Y spoke.

http://www.realoem.com/bmw/showparts.do?model=0503&mospid=47865&btnr=36_0171&hg=36&fg=10
And this would be the three-spoke wheel which we now know will fit early K bikes with slight mods...

Thank you TWB. It all makes sense now

Just a further note for those who might be considering the 4.5"x18" three spoke wheel for their earlier bikes so they can use a radial tyre of 160/60ZR18 proportions: The silver cast rear rim is the same part number between the 16 valve K100RS/K1100RS/K1100RT and the R850R/R1100R/R1100RS/R1100RT models, 36 31 2 311 275, and the wheel studs are the same length and diametre between these models as well.

Well there we are, the Avon roadriders are on and just for interests sake they do what Avon say on the box , no white line jumping mayhem scenarios !
An improvement on the lasertecs without a doubt and thus so far i`m rather pleased. Tomorrow a trip ; 300 miles from Bideford Devon to Bradford ,Yorkshire.
Weather ; light rain expected, lets see if Avons`other on-the-box boast is also correct.

Back !
Long wet trip back yesterday , mostly motorway , a lot of filtering, the Avons were superb both in wet and dry conditions.

Hello. I kinow this is a very old thread, but it seems to have a lot of good info/advice regarding tyre choices. Judging by what has been written, it looks like a toss up between the Pirelli Sports Demon and the Avon Road Rider. The sizes recommended seem to be 110/80 V18 Front and 140/80 V17 Rear. I have a 1987 K100RS that I bought about a month ago. It came with fairly new Pirelli tyres (lots of tread) MT08 (rear) and MT09 (front). The sizes however are different from the recommended sizes for the Sport Demon and Road Rider, they are: 130/90 17 68V (rear) and 100/90 18 56V (front). Me no understandi! Like, will the recommended sizes (for the new ones) fit my bike OK?
BTW, don't buy the MT08/09's, they white line violenlty even in the dry (scary at 90mph!) Terry the Dactyl.

Hi Tery, original size of K was 100/90 V 18 and 130/90 V 18, but you can put 110 front - 140 rear, with V speed index (up to 240 kmh). i just changed and put Dunlop Arrowmax 100 front, 130 rear, rather good but not expencive. In UK you have a better choice and better prices (check motorworks)-

Pirelli MT 8 maybe suitable for winter, but not choice for K bike.

Regards

Thanks Nino, I now know what the original sizes are, and that I can fit the Sport Demons or Avons - they are both about the same price as far as I have seen, so it will come down to my personal choice I think (I feel like Simon Cowell having to vote of one of the best singers in the competition!). Thanks again. Terry.

We like our roads twisty up here in the Northeast USA. Just about the end of motorcycle season here in New England and rode my rear metzler down to the core before my friends finally did an intervention (ha)! Wasn't too happy with this tire as it was fatter than stock tire and required more effort in the corners. The front metzler was loaded with ribbing, great for stopping, but caused front end vibration at higher speeds (>90MPH).

After much research I came up with:

Front: Bridgestone Battlax B45 110/90 R18 V-rated Bias Ply

Rear: Bridgestone Spitfire S11 130/90 R17 H-rated Bias Ply

The new Spitfire is much more responsive in the turns, and very stable at "freeway" speeds. The Battlax is otherwise a fairly standard tire used on BMW's for the past few years, so nothing new to report here.

The most important factor was to have bias ply's on both. One never combines bias plys with radials unless racing.

Was a bit concerned about combining H-rated and V-rated, but factory allows for this. Obviously the v-rated in front for stability and breaking at higher speeds. The h-rated in the rear is fine for New England which has a premium of 2-lane blacktops. I do shoot down the freeway on occasion, but rarely at speed.

Welcome to the forum. When you get a mo' pop over to the member's intro page and introduce yourself. I note you suggest an overwidth front tyre...

The stock tyres on an RT (and an RS, etc) are:

100/90-18
130/90-17 (except for 120/90-18 on drum brake models)

But stacks of us use:
110/80-18
140/80-17

With no ill-handling effects and plenty of kilometres of tyre life. The Pirelli Sport Demon is one in particular that gets good reviews. Let's hope you're not 'breaking' too much when you're 'braking'.

Cheers.

I use an Avon Storm 110/80-18 on the front and an Avon Azaro 140/80-17 on the rear. The 140 is the correct tyre according to the tyre spec sticker under the seat of my K100RS M Sport.

Probably won't be able to find replacements for the rear but I understand that Michelin make an adventure radial in 140/80-17. The Michelin Anakee from memory. I would rather go this way than go back to bias belted tyres.

First choice is Avon Azaro rear, 140/80ZR17 and Storm ST front 110/80ZR18. Second choice is the Michelin Ankakee 2 rear 140/80R17 (130/80R17 if you prefer light and fast steering or have a drum brake K75) and the Pilot Road 3 front 110/80ZR18. Both of these tires will last 10,000 miles front and rear on our bikes, making them cost less per mile than a less durable bias ply tire.

I learned by accident that a 120/70ZR18 tire will fit our rims too. A shop was careless and mounted a tire this size to my bike. I noticed the difference in steering feel and checked the sidewall to see what size the tire was. The shop put the correct size tire on at no charge, but everyone likes different things so it is something to try someday perhaps.

With suitable sized radials available, there is little reason to fit a bias ply tire.

A later model 4.5X18 rear wheel from a 16 valve K will bolt directly to our final drive with no problem. Where you will have a clearance problem is with the stock exhaust collector. To make the later wheel fit the early K100 you have to use an aftermarket exhaust system or one from a 16 valve bike. Even then tire clearance is only a couple of mm. I have seen it done though.

I fitted on my K100 Michelin Active Pilot tyres. Normal sizes (110 and 130). Looks nice, but its winter in here so I cant say anything about how they handle.

At -12c at the moment I can understand why.

Yep.. And the snow (about 30-40cm) is a kind of a problem too. Here's some cams from Pori:

http://www.pori.fi/pori-info/nettikamerat.html