I’m sure this has been done before but this post is to document my fitting of wider wheel and radial tyre to a 1993 K75S
Old combination – 3 x 17 - 3 spoke wheel – Maxxis 130-90-17 tyre
New combination 4.5x18 - 3 spoke wheel – Bridgestone 160-60ZR18 tyre
I believe the new wheel is standard on K1100RS, K100RS and K1.
I had it powder coated and modified it to fit a right angled valve.
The new tyre is 20mm wider than the old one and 12mm smaller diameter (as the old one is very worn that’s probably nearer 20mm
Theoretical sizes from a web based calculator (
https://www.rbracing-rsr.com/tirediamcalc.html)
130/90/17 = 666mm 160/60/18 = 649 Which gives 17mm difference or about 2.5%
Also I believe the new wheel centreline is 12mm further away from the diff mounting face.
Comments on fitting.
Firstly and most important the new wheel and tyre bolts up and fits in place of the old one. There is about 4mm clearance between the swingarm and tyre when using the standard 2mm spacer.
The existing stand does not fit. A K1100 stand does not fit. In both cases the left hand leg needs modifying.
Stand Modification
I chose to mod the existing stand. Basically I bent the left leg out, cut a piece out of the bottom and welded it back up again. I chose to cut out the cross brace then weld a new one in afterwards. I would recommend you could probably get away without doing this and avoid issues re-aligning the top pivot bushes. Note you can take the opportunity to fit grease nipples by tapping the existing holes M6
I also moved the silencer out about 8mm by cutting its support bracket stubs and adding some washers. Again this might not be absolutely necessary.
You do not need to remove the brake caliper or lift the bike to fit the wheel. It’s far easier to remove the silencer. If everything is greased up with new clean fasteners it comes off easily. Wheel slots straight in and wheel bolts are also easy to get at.