Can anyone confirm for me that a 140/80/17 rear will fit a standard K100RT?

Yep they do the job just fine.

I believe they must be a matching tyre set front and rear if you do the +1 oversize - eg Pirelli Sport Demons.

Fitted 110/80 - 18 & 140/80 - 17 Sport Demons to my 11/87 Basic last weekend.
Looking forward to trying them out now.

andyb wrote:I believe they must be a matching tyre set front and rear if you do the +1 oversize - eg Pirelli Sport Demons.

Don't have to be matching but some tyres do work well with a match. I used to run a Bridgestone BT045 on the front and a Michilin Macadam in the recommended sizes and it was a good combo. I do recall TWB saying that he liked the sport demon on both ends and felt it worked better than having a combo.
If you have a problem with a combo the manufacturer will always blame the other brand.

A Japanese tyre engineer is drinking warm saki along with his Italian, American, English and German tyre engineer mates, who're drinking red wine, steins of strong beer, Pepsi, and gin & tonic, respectively. They're slurring and laughing whilst discussing, through sign language and sketches on serviettes (napkins), tyre design, rubber compounds, traction, silica content, adhesion limits, wear characteristics and marketing. The night ends in a blur.

The next week at their respective factories they're attempting to recall the methods each one drunkenly mentioned as to why their particular tyre design is superior, but neither can remember exactly what was said. In the end they give up and design their front tyre to go with their back tyre, as intended.

The moral of the story is: One brand of tyre wasn't intentionally designed to be fitted to the same bike and to follow another brand of tyre through a bend or down a long stretch of highway, although you might get lucky now and again.

...or, drink what the other is drinking if you want to know what he is thinking.

+1 Daz.................................. I'm sure I read it in the operators manual. We could use some warm saki down here, the grey weather is setting in.

Must admit that I am very dissappointed with the tire choices available on the shelves here in Perth, went to 4 shops and they had either BT045s, Marathons and/or the Lasertecs. I originally wanted to put on a pair of Sport Demons but no one had them, ended up with old school Metzeler Lasertecs, in +1 sizes. Changed both front and back. Even though the original front Macadams had pleanty of thread, the original tires was pretty old. Rode 50+km to scrub them and so far they seem pretty decent. The new tires allow me lean much lower then I was comfortable, with the old tires.

What pressure do you all recommend I should run?

I just got the sport demons 140/80-17 and 110/80-18 installed the back tire 2 weeks ago feels great will try to do the front tire this week . Got them from Motorcycle super store around 230$ for the set

I'm a bit confused. The manual says 130/90-V17, but the sticker on my bike says 120/90-H18 (sic). Not sure what year the manual is, or for that matter what year the sticker is either.

I'm running a Bridgestone Spitfire 130/90-H18, and after about 800 miles it runs very quiet and feels very tight in the curves.

I assume a 140 width will work since others have tried it, but what about tire height? People have spec'd /80, but BMW is recommending /90.

So, the full question is; will a 140/90-17 (H or V rated) do the job?

My bike is a 1985 K100RT and the sticker shows 100/90/18 front and 130/90/17 rear. Looks like different markets and years might have different sizes.

Did you look at the rear wheel's tyre size? If it's an 18" wheel it's got a drum brake, ala K75.
A 140/90 series wouldn't be available, nor would it be wise due to being too tall. 140mm tyres with an 80 profile are acceptable where a 130/90 is specified. We assume this is a K with a 17" rear wheel and disc brake.

AJ.Valente wrote:I'm a bit confused. The manual says 130/90-V17, but the sticker on my bike says 120/90-H18 (sic).

I'm running a Bridgestone Spitfire 130/90-H18,

So, the full question is; will a 140/90-17 (H or V rated) do the job?

So your sticker says to fit an 18" tyre and you have an 18" Spitfire fitted. It is impossible for a 17" tyre(eg 140/90-17) to fit an 18" rim to begin with.
Your bike is an '85 K100RT (from your profile).
Standard would be F 100/90-18 and R 130/90-17.
+1 sizes would be F 110/80-18 and R 140/80-17.
If you do have an 18" rear wheel/tyre it is from a K75 and would have a drum brake.
Has someone fitted a K75 rear end at some stage? If you have an 18" rear and the standard tyre is 120/90, your 130/90 is already a plus 1 size.
If your wheel is a 17 but the sticker says 18, maybe the rear panel with the sticker has been changed at some stage and its just the wrong sticker for your bike (K75/100 use the same rear bodywork)

Al

+1 to what AL said and is the bike an ex police because that would explain the different tail section with the wrong sticker.
An 80% profile on a 140 is almost the same as a 90% profile on a 130 so the tyre diameter is the same or close and will only lead to less than 1% speedo error.

could the rear be off a later series bike ....k1 or 16 valve something ? my wide one is 18 inch

charlie99 wrote:could the rear be off a later series bike ....k1 or 16 valve something ? my wide one is 18 inch

k1/16v/1100RS are wide 3 spokes wheels to take a 160/60-18
K75 is a narrow 8 spoke(4 Ys) to take a 120/90-18
A very big difference.
Al

charlie99 wrote:could the rear be off a later series bike ....k1 or 16 valve something ? my wide one is 18 inch

No, just a typo. It's a 17" tire, sorry bout that.

But you got some heads whirring hey