Gents, Looking for some counsel as am sure someone here has contemplated or has this size on their vehicle.

I have currently have 275 40 18 rear tires on OEM Jaguar BBS wheels. Just had the springs changed and the vehicle sits a bit lower hence considering going to 35 18.

Any input on having the 285 35 18 over the 275 35 18 would be most appreciated.

 

Don't really get what you are asking for, but I presume 5 minutes with a ruler will give you all the answers and confirmation you are looking for.
As you already have 275 (I presume /40, not /35), its just a matter of some plus and minus.