What were Jimmy's boots he wore all of the time?

I know that he wore some engineer boots in Rebel Without A Cause, but he also wore what looked like cowboy boots or zip boots that looked like cowboy boots a lot. I have seen many photos of hime wearing them, from photos of him with his triumph (both his T100 and TR5) to photos of him at the races with his porsche speedster. Does anyone know what brand and model these were? Maybe even if they are still made by the same company or if a replica is made? Again, I am not talking about his engineer boots with the buckle, the boots I am speaking of have no buckle at all.

Thanks,
Charlie