well for 1 the poor sap who has to replace it gets a bath when the foam turns back into water and when it turns back in to a liqud and it vibrates and starts eating away at your tire from the inside out then if you unlucky and it's a front tire that has the crap in it and with the temp from the brakes bakes the **** to your wheel and u gotta buy a new wheel cause they don't wanna try and chisel the now cement like fix a crap off your rim just not a good thing to put in your tires if u got a run flat run it flat or put your spare on if u don't fix a crap is no good thing for tires