Different tyre weights = incompatible?

[MarkDavis]

Got some 225/45/17 Conti CS3s fitted today at Stratstone for what I thought was a bargain price of £120 per tyre.

I was going to get some F1 Assym 2s but they said that the weight of the tyre as stated in the specification isn't what was recommended. They said that they would fit them if I really wanted to but it wasn't strictly within spec because the Assym 2s were a lighter weight.

Have to admit I've never heard of tyre weights - I thought the 225/45/17 and speed rating was all you needed.

Anyone able to enlighten me on this?

 

[MarkDavis]

Well, I did some research.....

Blackcircles suggest insurance may be invalidated if you choose the wrong weight rating: http://www.blackcircles.com/general/load-rating

The CS3s Stratstone fitted are marked "225/45 R17 W (94) Extra Load" and therefore 670kg.

Assym 2s appear to come in 225/45 R17 Y (91) and 225/45 R17 Y (94) and therefore rated as sufficient to carry a max load of 615kg and 670kg respectively.

Sounds like Stratstone only carried the 91 rated tyres and not the 94 hence their advice, which although technically correct, was a bit misleading...