Wheel spacers, or whole new wheels?

---please read before submitting pole---

Today I just put some 31x10.5 Goodyear MT/R tires on my Jeep, replacing old BFG A/T KO tires (metric about 28"). This is a two part explanation, so bear with me.



First, I'm still running the stock 15x7 wheels which I have absolutely no problem with, but the man at Tire Factory suggested that I get 15x8 rims because the tires will wear better (on road) than they will with my current 15x7 rims.



Second, since the tires rub a bit when the steering wheel is maxed out I asked the same guy at Tire Factory about wheel spacers and if they would solve that problem. He said they would, but new rims would also move the wheel far enough away so that they don't rub.



If I were to get new rims I would probably buy a set of 5 and get a fifth tire which would run me about $700 - keep in mind I just spent almost $1k (900 after mail in rebate). As I said, I am very happy with the look and performance of the stock wheels, so unless I will have a noticeable benefit from buying 1" wider rims I would just like to stick with them and get wheel spacers - which will be ~$200.



Finally, if people think wheel spacers will be sufficient then how do I know what size to get?



I look forward to people's recommendations and opinions.