"Wide" tires on narrow rims?

I need to replace the tires on my '82 Van Diemen.

I t has 6" wide front and 8" wide rear rims, both 13" diameter.

I'm thinking of fitting 7" wide fronts (7.0x20.5/13) and 9" wide rears (9.0x22.0/13).

The car is in a "formula libre" category so not running normal FC tire sizes is OK.

Any thoughts or comments on the suitability of using tires 1" wider than the rims would be appreciated.

The other option available to me is 6.0" or 6.5" wide fronts and 8.2" wide rears.

Thanks in advance.

"Wide" tires on narrow rims?