Misc. Tire/Rim sizing

[Trpval]

Have 15 x 7 wagon wheels with 30 x 9.5 tires. Tires seem a bit narrow on these rims. Would going to a 15 x 8 make any difference or just tire size?

 

[Belizean]

I have 2 sets of wheels that are all 15 x 7. 1 set I have 31 x 15 x 9.5 tires. 1 set I have 33 x 15 x 10.5 tires. I actually like a narrower tire. Some like fatter. I don’t think I can go any wider though with 15 x 7.