Wider tire size

Mornin' All,

I own a '72 Demon 340 in stock form. As most know, it came with GOODYEAR POLYGLAS E70-14 tires.

Presently I have B F GOODRICH RADIAL T/A, P205/70SR-14's on it.

I'd like to go to a wider tire size using the same stock rim. I'd prefer not to have to change the speedometer gear.

Any suggestions as to the optional sizes?

Thanks!