It's doable if you don't go too heavy. Keep in mind, as you increase the tire dia. there will be more stress on the axles, bearings, axle shafts, gears, u-joints, transmission, ball joints, steering system, etc. Especially with the additional power mods. There are other issues that will crop up that he will have to be willing to live with also. To help some, stay with a larger wheel, say 20's so you don't get excessive sidewall flex.