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1Back to top Go down   Bmkk100RS rear Tyre Empty Bmkk100RS rear Tyre Sun Sep 11, 2022 12:51 am

tassoni

tassoni
New member
New member
Greetings guy's, can anyone please tell me what the maximum size of the rear tyre on an 1986 BMWK100RS, I recently took my bike to the shop and got some new tyres put on, now this is where it gets annoying, the manual states 130/90 and the shop gave me 130/70, I didn't notice it then, but when i got the bike back home I checked it out and it looks like i am riding on a rear bicycle wheel, I need to get the tyre replaced but I need you guy's to please advise me what the maximum size for my bike can be or should be.

    

2Back to top Go down   Bmkk100RS rear Tyre Empty Re: Bmkk100RS rear Tyre Sun Sep 11, 2022 12:57 am

Two Wheels Better

Two Wheels Better
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Moderator
The rear Y spoke wheel should be able to handle a 140/80-17 without dramas, and the stock 130/90 size, but never a 130/70. That is a wanker move on the part of your tyre changer. Did they not read the tyre's sidewall? I'd be knockin' on their door first thing telling them they need to remedy the situation. A 70 series tyre is what's commonly used on a much lighter motorbike than a typical K100.


__________________________________________________

1970 R60/5, '77 R75/7-R100, '85 K100'87 K75C, '87 K100RS, '93 K11-K12 Big Block, '93 K1100RS, '95 R100-Mystic, '96 K1100RS, '98 K1200RS, '00 K1200RS, '02 K1200RS, '03 K1200GT, '04 R1150R'04 R1150RT, '05 K1200S, #1 '06 K1200R, #2 '06 K1200R, '07 K1200R, '09 K1300GT, '13 R1200RT-P & 2022 S1000XR

"Do you ever read any of the books you burn?" "That's against the law!" "Oh, of course."
~Ray Bradbury, science-fiction writer (22 August 1920 - 2012)
    

3Back to top Go down   Bmkk100RS rear Tyre Empty Bmkk100RS rear Tyre Sun Sep 11, 2022 1:08 am

tassoni

tassoni
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Thank you for the quick reply and the dimensions, I will be taking it back to the shop and telling them how stupid they are, I really thought if I had a 130/90 installed why in the living hell would they throw on a 130/70, just stupid I'm guessing.

    

4Back to top Go down   Bmkk100RS rear Tyre Empty Re: Bmkk100RS rear Tyre Sun Sep 11, 2022 1:32 am

Two Wheels Better

Two Wheels Better
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12 years ago I was riding south through Cairns having spent a month fiddling about where I could get to in far north Qld. My K100RS needed a new rear sneaker very bad. I stopped in a shop and all they had was a 130/70-17, but it was good 'n' cheap like me at the time. It lasted from Cairns to Beenleigh. It was frightening to ride on with camping gear and the usual moto travel kit at motorway speeds and in corners, any corner. It was my choice. It was my money. I accepted it. I would never do it again.


__________________________________________________

1970 R60/5, '77 R75/7-R100, '85 K100'87 K75C, '87 K100RS, '93 K11-K12 Big Block, '93 K1100RS, '95 R100-Mystic, '96 K1100RS, '98 K1200RS, '00 K1200RS, '02 K1200RS, '03 K1200GT, '04 R1150R'04 R1150RT, '05 K1200S, #1 '06 K1200R, #2 '06 K1200R, '07 K1200R, '09 K1300GT, '13 R1200RT-P & 2022 S1000XR

"Do you ever read any of the books you burn?" "That's against the law!" "Oh, of course."
~Ray Bradbury, science-fiction writer (22 August 1920 - 2012)
    

5Back to top Go down   Bmkk100RS rear Tyre Empty Re: Bmkk100RS rear Tyre Mon Sep 12, 2022 10:12 am

92KK 84WW Olaf

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Life time member
Life time member
tassoni wrote:Greetings guy's, can anyone please tell me what the maximum size of the rear tyre on an 1986 BMWK100RS, I recently took my bike to the shop and got some new tyres put on, now this is where it gets annoying, the manual states 130/90 and the shop gave me 130/70, I didn't notice it then, but when i got the bike back home I checked it out and it looks like i am riding on a rear bicycle wheel, I need to get the tyre replaced but I need you guy's to please advise me what the maximum size for my bike can be or should be.
The tyre should be fine, I run 140/70 but you can use 130/80 130/90 140/80 if you prefer. It can deend on your preferred tyre choice too. 150 does not have side clearance to fit.

You need to pump it to 42psi for solo riding.


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 49,840 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 42,640 miles.

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

6Back to top Go down   Bmkk100RS rear Tyre Empty K100RS Tyre options Mon Sep 12, 2022 6:16 pm

redrockmania

redrockmania
Silver member
Silver member
Tyre size options are dependant upon how stock you wish to be. 
On my 1983 K100RS I decided to make various changes and have successfully fitted a Pirelli radial 160/60 R18 to a 3 spoke K1100 18" x 4.5 rim. This has been done in conjunction with other upgrades and modifications. 
Centre Stand Modification: I modified a K1100 centre stand by widening it. I then fabricated a steel plate which fits between the centre stand mount and the base of the engine block (the K1100 has different mount hole positions to the K100 one).These centre stand modifications have made it easier to lift the bike onto the stand. 
Exhaust System Modifications: I have fitted an aftermarket exhaust collector and a carbon fibre muffler for weight reduction. To get muffler clearance with the left side of the tyre I machined an aluminium spacer that fits onto the left foot peg plate.
The above mods were done with 2 objectives: benefit from a radial rear tyre with improved performance; reduced weight.

    

7Back to top Go down   Bmkk100RS rear Tyre Empty Re: Bmkk100RS rear Tyre Tue Sep 13, 2022 5:04 am

92KK 84WW Olaf

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Life time member
Life time member
160/60 is the correct size for a K1100 18" rim. It,s for K1100RS but the 18" rim also fits a K1100LT and there is clearance for the 160 on the K1100LT and RS.

K1100LT rear rim is 17" and you are back to 140 because of the rim size, not because of clearance issues.


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 49,840 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 42,640 miles.

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

8Back to top Go down   Bmkk100RS rear Tyre Empty Re: Bmkk100RS rear Tyre Wed Sep 14, 2022 9:58 pm

duck

duck
Life time member
Life time member
92KK 84WW Olaf wrote:160/60 is the correct size for a K1100 18" rim. It,s for K1100RS but the 18" rim also fits a K1100LT and there is clearance for the 160 on the K1100LT and RS.

K1100LT rear rim is 17" and you are back to 140 because of the rim size, not because of clearance issues.

150/70 works fine on the 17" 3-spoke rear. I run 150/70-17 rear radials on the 17" 3-spoke - K75, K100 and K1100LT.

I run 130/80-18 radials on the Y-spoke rear. 110/80-18 radial in the front.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

9Back to top Go down   Bmkk100RS rear Tyre Empty Re: Bmkk100RS rear Tyre Thu Sep 22, 2022 7:15 am

92KK 84WW Olaf

avatar
Life time member
Life time member
redrockmania wrote:Tyre size options are dependant upon how stock you wish to be. 
On my 1983 K100RS I decided to make various changes and have successfully fitted a Pirelli radial 160/60 R18 to a 3 spoke K1100 18" x 4.5 rim. This has been done in conjunction with other upgrades and modifications. 
Centre Stand Modification: I modified a K1100 centre stand by widening it. I then fabricated a steel plate which fits between the centre stand mount and the base of the engine block (the K1100 has different mount hole positions to the K100 one).These centre stand modifications have made it easier to lift the bike onto the stand. 
Exhaust System Modifications: I have fitted an aftermarket exhaust collector and a carbon fibre muffler for weight reduction. To get muffler clearance with the left side of the tyre I machined an aluminium spacer that fits onto the left foot peg plate.
The above mods were done with 2 objectives: benefit from a radial rear tyre with improved performance; reduced weight.

Not sure I understand this. I have put the complete K1100 stand assemblies on all my 2v Ks and its a straight change, same gearbox mounts etc. . "


Centre Stand Modification: I modified a K1100 centre stand by widening it. I then fabricated a steel plate which fits between the centre stand mount and the base of the engine block (the K1100 has different mount hole positions to the K100 one).These centre stand modifications have made it easier to lift the bike onto the stand".


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 49,840 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 42,640 miles.

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

10Back to top Go down   Bmkk100RS rear Tyre Empty Re: Bmkk100RS rear Tyre Thu Sep 22, 2022 10:35 am

Two Wheels Better

Two Wheels Better
Moderator
Moderator
...when using a 160/60R18 tyre & wheel from a K1100RS, as well as a K11 centre stand, it is necessary to modify the stand to clear, when fitting these to a 2V  K. On mine it was only massaging a few mm's off the inner edge of the left foot.


__________________________________________________

1970 R60/5, '77 R75/7-R100, '85 K100'87 K75C, '87 K100RS, '93 K11-K12 Big Block, '93 K1100RS, '95 R100-Mystic, '96 K1100RS, '98 K1200RS, '00 K1200RS, '02 K1200RS, '03 K1200GT, '04 R1150R'04 R1150RT, '05 K1200S, #1 '06 K1200R, #2 '06 K1200R, '07 K1200R, '09 K1300GT, '13 R1200RT-P & 2022 S1000XR

"Do you ever read any of the books you burn?" "That's against the law!" "Oh, of course."
~Ray Bradbury, science-fiction writer (22 August 1920 - 2012)
    

11Back to top Go down   Bmkk100RS rear Tyre Empty Re: Bmkk100RS rear Tyre Thu Sep 22, 2022 11:16 am

duck

duck
Life time member
Life time member
Two Wheels Better wrote:...when using a 160/60R18 tyre & wheel from a K1100RS, as well as a K11 centre stand, it is necessary to modify the stand to clear, when fitting these to a 2V  K. On mine it was only massaging a few mm's off the inner edge of the left foot.

Isn't the root cause of this the fact that a monolever rear end is shorter than a paralever rear end? (So the rear wheel is farther forward on the monolever setup.) I'm pretty darned sure that if you put a paralever rear end on a K75/K100 then no mods would be required to run a 160/60-18 with a K11 center stand.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

12Back to top Go down   Bmkk100RS rear Tyre Empty Re: Bmkk100RS rear Tyre Thu Sep 22, 2022 12:40 pm

Two Wheels Better

Two Wheels Better
Moderator
Moderator
Yeah, that makes sense. It was only the edge of the 'wider' tyre making contact. A grind here n there made it clear. A Paralever gearbox & swingarm on an Monolever K would seem to pose no clearance issue with the '160' tyre.


__________________________________________________

1970 R60/5, '77 R75/7-R100, '85 K100'87 K75C, '87 K100RS, '93 K11-K12 Big Block, '93 K1100RS, '95 R100-Mystic, '96 K1100RS, '98 K1200RS, '00 K1200RS, '02 K1200RS, '03 K1200GT, '04 R1150R'04 R1150RT, '05 K1200S, #1 '06 K1200R, #2 '06 K1200R, '07 K1200R, '09 K1300GT, '13 R1200RT-P & 2022 S1000XR

"Do you ever read any of the books you burn?" "That's against the law!" "Oh, of course."
~Ray Bradbury, science-fiction writer (22 August 1920 - 2012)
    

13Back to top Go down   Bmkk100RS rear Tyre Empty Re: Bmkk100RS rear Tyre Thu Sep 22, 2022 1:02 pm

duck

duck
Life time member
Life time member
redrockmania wrote:The above mods were done with 2 objectives: benefit from a radial rear tyre with improved performance; reduced weight.

A 4.5x18 weighs more than a 3x17.  Not only that but the heavier 4.5 rim is farther out so it has even more inertia and therefore will not accelerate as fast as a bike with a 3x17.

The 3x17 also requires less lean angle and has a tighter turning radius so the bike is more nimble in turns on a 3x17.

Wider tires do have a larger contact patch and better traction but I can scrape pegs on a 3x17 with a 150/70-17 radial and don't need any more traction than that. If K75 and K100s had more torque then it might make sense to run wider tires but neither bike has enough torque to spin up a tire coming out of a turn.

The wider tires also hydroplane more easily. My K1100RS hydroplanes at about 70 MPH but my K1100LT gets up above 75 before it starts to hydroplane.

Those are the reasons that I think a 3x17 makes more sense performance and weight-wise on a K75 or K100.

JM02, YMMV


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

14Back to top Go down   Bmkk100RS rear Tyre Empty Re: Bmkk100RS rear Tyre Thu Sep 22, 2022 2:53 pm

jbt

jbt
Platinum member
Platinum member
Riding various K75, K100, K1 and k1100LT since 1997, I've tried various combinations of rims, with the K1100RS specs (17 inches front, 18 inches front) and mixed configurations (17 inches everywhere and 18 inches everywhere). 
My conclusion is the wider the rims are, the worst is handling. 
I never found any improve on grip with wider rims. But the ground clearance is then reduced with a 17 inches front wheel, and the bike is  more difficult to handle and to lean in cornering. 
Both 18 inches rims gave interesting results, but still with the resistance to lean due to the wide rims. 
The OEM rims set on the K1100LT is amho the best choice that allows to ride fast on twisty roads a 300 kg motorcycle with no fatigue. It's natural, safe and effortless, whereas the K1 is much more demanding on the same roads. 

Wide tyres is a stupid fashion, completely unnecessary.


__________________________________________________
Let us enjoy the transient delight
That fills our fairest day.
    

15Back to top Go down   Bmkk100RS rear Tyre Empty Re: Bmkk100RS rear Tyre Thu Sep 22, 2022 3:33 pm

duck

duck
Life time member
Life time member
jbt wrote:Riding various K75, K100, K1 and k1100LT since 1997, I've tried various combinations of rims, with the K1100RS specs (17 inches front, 18 inches front) and mixed configurations (17 inches everywhere and 18 inches everywhere). 
My conclusion is the wider the rims are, the worst is handling. 
I never found any improve on grip with wider rims. But the ground clearance is then reduced with a 17 inches front wheel, and the bike is  more difficult to handle and to lean in cornering. 
Both 18 inches rims gave interesting results, but still with the resistance to lean due to the wide rims. 
The OEM rims set on the K1100LT is amho the best choice that allows to ride fast on twisty roads a 300 kg motorcycle with no fatigue. It's natural, safe and effortless, whereas the K1 is much more demanding on the same roads. 

Wide tyres is a stupid fashion, completely unnecessary.

When I built my K75 Frankenbrick it ended up essentially being a K1100RS with a K75 motor. I decided on using the K1100LT wheels and it isn't a "pig" in the tighter turns like my K1100RS or K1 can be. (But I still enjoy riding the 4V bikes with wide wheels.)

Bmkk100RS rear Tyre K75f.nordland


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

16Back to top Go down   Bmkk100RS rear Tyre Empty Re: Bmkk100RS rear Tyre Mon Sep 26, 2022 4:46 pm

92KK 84WW Olaf

avatar
Life time member
Life time member
jbt wrote:Riding various K75, K100, K1 and k1100LT since 1997, I've tried various combinations of rims, with the K1100RS specs (17 inches front, 18 inches front) and mixed configurations (17 inches everywhere and 18 inches everywhere). 
My conclusion is the wider the rims are, the worst is handling. 
I never found any improve on grip with wider rims. But the ground clearance is then reduced with a 17 inches front wheel, and the bike is  more difficult to handle and to lean in cornering. 
Both 18 inches rims gave interesting results, but still with the resistance to lean due to the wide rims. 
The OEM rims set on the K1100LT is amho the best choice that allows to ride fast on twisty roads a 300 kg motorcycle with no fatigue. It's natural, safe and effortless, whereas the K1 is much more demanding on the same roads. 

Wide tyres is a stupid fashion, completely unnecessary.
I have both the RS and LT wheels for my K1100LT. I too have tried the various combinations and most definitely the LT wheels [18 front /17 rear] make it much more nimble.


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 49,840 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 42,640 miles.

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

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