In the late 70's/early 80's I had a Bonnie and I put some OKO (UK sealant) in the tyres (to keep the UK theme).  The first time I took it on a motorway I got up to 80 (mph) and it vibrated a bit.  I thought it might just be one of those that you can ride through so I carried on going.  At 100 it was still there so I decided to slow down.  As I was slowing down I realised that it was still there so I stopped on the hard shoulder.  The back tyre was completely flat and there was green snot all over it.  The inner tube was shredded.  I still don't know if it helped or not.

Tire valves are made of brass. After a couple of months the sealant leaks a little to the valve and oxidizes the brass, turning the whole thing nonfunctional. I've learned that the hard way, when I stopped at a roadside gas station one night, returning home after a day long ride, and tried to fill the tire. As Serowbot said, the valve sticks to the inward position so all I had was a deflated tire. And... the repair shop was already closed. So, use that goo if you want but don't leave home without a spare valve.

I believe there are different formulations of sealant.  Once I bought the cream colored Monkey Grip stuff and used it in my lawn tractor tires.  A few months later I noticed the tires were oblong and mishapen.....kind of like a bagle where one side is larger than the other.  I took the tires off the rim and found the sealer had dissolved the rubber covering the chords and the whole inside of the tire had strings of loose chord.  I had to buy new tires and from then on I only use the Green colored slime.  I have the green Slime in all my mower and tractor tires and I have never had any issues with the valve stems corroding.  I have not used in in a street driven motorcycle - but I have used it in my mowers and dirt bikes as we have lots of vegetation with small thorns that make tiny little holes.

Doug B wrote on 06/24/13 at 21:56:36:


I think you'll like it. So far it has sealed a slow leak completely for more than a year, tire balance is slightly improved, no problems with valves leaking or getting stuck, though with the Ride-on I only have to add air when it gets significantly colder.