I’d imagine that sometimes boxes of tyres may sit in less than perfect conditions for the preservation of tyre quality between leaving the factory and the consumer.
Michelin probably will accept a set percentage of wholesale volume as “warranty” before wanting to see the tyres physically returned and Wiggle will have a matrix of cost vs reputation damage. A customer who’s got a few orders up, has a photo showing a fault is likely to respond positively to a prompt and decisive action. Dragging things out cost them staff time, and risks reputation...
Reminds me of a game a colleague played with Australian Customs and getting GST rebate. His chasing a circa $50 rebate. It took 3 months of e-mails, phone calls and some letters before finally he got his $50. Would have cost us taxpayers thousands in staff time. It served to highlight that a small loss can be worn quickly and time only increases cost.