I bought some new Pirellis a while ago. 750R16 Dakkars. And split rims to suit.

Took ages to establish the tyres were the problem - eventually did so by bolting on a set of extremely worn Hancooks and driving them up to the tyre place. He had to admit that the problem was either his tyres or his rims, changed to another set of rims - still a problem.

Agreed to replace them, made arrangements with, and then sent me to the local Pirelli distributor for the changeover to new ones. They tried to make me go through a process to prove the problem was actually the tyres. After steam stopped coming out of my ears, and polite but assertive language from my mouth, they agreed that all had been that was necessary, and fitted up a new set - which were perfect.