We put a set on our 4240 which we mow with.  Knocked them off the rim a couple times but never had anything go through one yet.  We've wore about 2 layers off them since we put them on quite a few years ago.  I think they're like 40 ply so have plenty to go.  They aren't good for high speed applications.  We were going to put a set on a spray tender once but said they would overheat running them highway speed too long.  They have a real high speed rating but it's for a short duration.