I broke one of my rims last night in my XL5 rustler. The rims that are on there are 2.8". It seems very hard to find tires that size. The guy at the hobby shop said that the stock tires on the rustler are too big, and I will get better run time/more rpms if I went to a smaller diameter tire. Is this true? Or should I just replace the stck rim?

If you don't mind replacing all four wheels, then I'd say that's the way to go. I'm pretty sure what that guy said is true. When I changed the tires on my Stampede from the heavy stock ones to a set of lighter and smaller diameter stadium truck tires, I noticed better run times myself. You'll have a lot more tires you're able to used on 2.2" rims, too.

I bought 4 new rims yesterday. The 2.2" with a set of pro-line tires. But the over-all diameter isn't much smaller actually. There is more sidewall of the tire to make up for the smaller rim size.