-
I'd not worry about grip, unless I found issues in the wet, but then I've driven a car on ats own brand cheapies that had no grip wet or dry from new. Ever seen a diesel Citroen bx wheel spin from standing start on an incline? Have used slime (or the Wilko equivalent in orang) to sort out leaking and even porous rims.
Used the same stuff on motorbikes and not had any balance or performance issues.
air appears to escape when parked over period of weeks, usually not tons but enough to need a good top up