Is it crazy to use an 18” rear wheel (stock) and a 17” SuperMoto rim on the front?

Does anyone use a setup like this?
Also can anyone tell me which rims are options for the front which will work, Excel 3” etc?
I use my bike mostly for hardpack dirt/gravel roads and crummy, pot holed, may turn to gravel twisty roads.
So I would like a more SuperMoto set up but being a cheap character I would like to purchase the rims one at a time I think a complete set typically runs $1250.00 US.

Any helpful comment or even just plan name calling is OK.

Thanks
Jim

 

I have the front and rear 17" rims and mine handles fine. The front is a 3" x 17" and the rear 3.5" x 17" and runs Dunlop Arrowmax GT401's rear 130/70-17 front 110/70-17.

Cheers