Just about to replace my Goodyear 235/60/18 103W tyres and see that for not much more the 235/60/18 107W spec has a C rolling resistance rating as opposed to an E. So in theory a big saving on fuel. The 103Ws are fitted to Q5 and the 107W are fitted to the Q7. Is there any downside to fitting the 107W on the Q5.? The tyre shop says no, but I assume the extra load tyre will have different handling??? Anyone looked into this?