You might have a problem finding a mechanic willing to install standard tires on R/F wheels.
I did it when returning a Mini Clubman at end of lease, and a tire shop reluctantly accepted to install two new tires non R/F, saying it will affect the car handling, and he couln't be held responsible bla bla bla....
As expected, it did affect nothing, the car handled just the same way it did with R/F.
Actually, Lemme rephrase that : it did affect my wallet
as the lease company auditor caught it and told me either to change those BRAND NEW TIRES for R/F, or expect BMW Lease to charge me for them (at a conveniently hefty rate, since anything BMW-installed seems in solid gold).
So I chose the former.
So in a nutshell, it is possible to substitute non R/F for R/F tires on the same wheels. It's worth it as long as the car is owned and does not face inspection (ie TUV / DOT etc..) too soon...