· Journeyman Human
Thats not supposed to be the case at all. Some lazy tyre fitters don't like cleaning it out before fixing the puncture, and it's an opportunity to sell you another tyre!Yes, using the can of gunk usually results in replacing the whole tyre. £176 is steep for 1 tyre though, I had two Goodyear Efficient Grip Performance 2 fitted at my house for £203 a few months ago.
Best to insist they repair or lose the business to an honest tyre service instead. They will quite rightly charge a little more for the time and materials to clean out the gunk, but it's not an issue.
Some tesla owners get similar rubbish from fitters who don't want to deal with the soundproofing foam thats in those tyres.