New Knobbies for the Coolster

The new knobbie tires came in a pair of Bridgestone Motocross M402's. The description in the Chaparral catalog says that they are suited for intermediate terrain, which suited me as about right for serious yard riding and casual track tracing. First thing up was to take off the rear tire. I had to HAMMER it off. It was really squeezed in the swing arm, I’ll come back to this. For now I needed to pull the brake disc screws, apply some "blue" medium strength thread locker and retorque. Next I had to remove the original tires. Do yourself a favor, if you plan on doing the replacement yourself, get a set of those Rim Protectors that are sold in most metric motorcycle catalogs. The anodizing on aluminum rims is a soft and easily scratches. I thought I was smart enough to figure something else to use, and although I ended up using the lips off an old plastic waste basket and taped my irons, it still put a couple of small marks on the rims. The right tool is so important. Putting the new tire on was easier than taking the old one off though and I seemed on track until I tried to shoe horn the tire, axle spacers, and disk brakes back into that aforementioned "son of monkey swing arm" I realized that there was no way I was going to make it go back in the way it came out. This next part is not recommended but I did it anyway. I sized up the spacers and it appeared that the swing arm to brake spacer was larger than needed due to the gap it was causing between the brake mounting plate. Some of us are lucky enough to have access to a hobby lathe, and against better judgment I machined off 0.25" off of this first spacer. This seemed to be enough, the whole tire assembly then fit snug but didn’t need the swing arm spread to make it happen. Also, when I checked the swing arm mounting bolt for the rear shock, I noticed some rust, so a liberal application of white lithium spray grease to this area should protect and lubricate (that's what I'm pointing to in the picture).
My test riders says that it is a definate improvement over the stock, turf friendly tires. Myself, I never really cared for the lawn, so let it have it.