I have a set of Cragar nomad 1's 15x8 , they have 3-3/4'' backspacing and -19mm offset I'm running 3.55 gear ratio. I was wondering what size I could go up to on the rear, and also what would be good on the front.
That 3 3/4" backspacing isn't going to work out very well. The tires will protrude passed the wheel well lip which will result in tire sidewall gouging. 4 1/4" or 4 1/2" backspacing works best with an 8" wheel. You can also review the wheel and tire data in the Garage section of this site.
3-3/4" will work on the back, but on the front you'll need to keep the tire narrow like a 215 or less. 4-inch is ideal for Mavericks. 4-1/4" will work, but 4-1/2" will rub leaf springs and frame rail. With the wheels you currently have, a 215/60-15 will work on the front, and a 245/60-15 on the back...
