My K1100LT was wobbling from side-to-side, both before and after I put on new tires. BMW Ventura was not able to get me in for an appointment in enough time for our club trip the Beemer Bash in Quincy, so they offered these trouble shooting tips:
1) Check for a bent rim
2) Check for warn tires
3) Check that both front and back tires are the same brand
4) Check BMW’s recommend tire size and approved manufacture
5) Check air pressure in tires
6) Check loose front wheel bearings
7) Check if back swing arm is loose
I was able to find and fix my problem. I had a combination of the above. I initially had worn tires and needed to replace them on a long road trip. The Honda shop, on the road, only had one tire that would fit the front and back rims, so I had them install the tires. Well the tires were not the same manufacture and both tires were radials. Neither tire was the recommended width or height.
When I took the bike to Dave Blunk at Sport Cycle Pacific,(805) 966-6508, he discovered that I also had very, very low air pressure in the new back tire. I also discovered from Butch, the service manager at BMW Ventura, that my bike was not approved for radial tires. Dave Blunk ordered two new tires and within 24 hours had them installed. He was 1/2 the price as the Honda shop.
So you see, I violated 4 of the 7 items to look for if your bike starts to wobble.