what size wheels are you banding and to what width
as a guide i would say get your head round the idea of either
low profile 40-35 for a square flat look
or a narrower tread slightly more profile for stretch
eg .15x7 alloy wheel could have a 195x40x15 for a square (and legal looking) look/fit
or 15x7 alloy could have a 165x50x15 for stretch that looks good but at a price including finding someone to fit them and having to run at 50 psi to stop any sidewall felexion , and avoid all potholes to avoid denting rim
it all depends on the wheels the tyres are going on and you buget