Tyre fitment question

[Saabyfox]

OK, a question for a tyre fitter or otherwise enlightened person.

I am looking to fit some winter/ all season tyres to my car, mainly as my route to work takes in a high percentage of ungritted muddy country roads. Grip has noticeably dropped in the last week or so to the extent that the traction control warning on my dashboard thinks it is a christmas light.

I am having trouble finding a rear winter/allseason tyre with the exact same fitment for my car ( front 245/40/18, rear 275/35/18).

Would it be possible to fit a 265/35/18 rear tyre on a rim meant for 275?
Or would it be a big mistake to fit the correct size of front and rear tyres, but mix brands on each axle? IE vredestein on the front, and say Kumho on the rears?

Advice appreciated.

Yours, mostly sideways,

Mark

[NormanD]

I can't see a problem, it's not as if you are going at high speeds on the tyres.

[Jaguar steve]

Should be OK as the proposed change in width is very small relative to the overall size.

Google The Wheel and Tyre Bible - sorry, I don't know how to link for you - there's all the info and dimensional calculators on there anybody could possibly need.