can some one help me with tyres.please

[daviesbike]

I have FE 20" wheels and they are getting very low now i have been let down by a tire place but i have phoned up a place about 70 miles away and the only size they have is 275-35-20

Will they fit my wheel i know 265-35-20 would fit but what about the extra bit ?

Stanfard tyres were 255-35-20

Any help would be great
Im not sure if my wheels are 8.5J or 9J i think they are 9J

Many thanks