+15mm or +30mm?

ive got a 98 frontier bagd and i want to run 22x9.5 rims but there are two different offset sizes, +15 and +30 which one should i roll with

Have you tried that size? I was told by a couple places that they would stick out to much.

Ive seen people running a 20x8.5 with a +40mm offset for frontiers. So I always figured I had to stay with the 8.5. I could be wrong though I dont know much about wheels.

neither one will tuck on a 9.5" rim.

If Russ says it won't work. It ain't happin, he knows his shit. Especially about offset. I've learned a thing or two from him on other posts

What if i find another 22 with a bigger offset. Would the 9.5 still work?

I would agree with the other guys with one exception. You didn't say if you were running 22x9.5's all 4 corners or just the rear. If just the rear, I'm setting my HB up for 22x9.5 with a +30mm offset but you have to have narrow the rear axle and the frame. The higher the offset the more wheel you tuck and make sure your hub bore is correct size to be hubcentric.

You would need at least 40mm of positive offset, and even then you may have problems with the tire rubbing the frame when you turn.