I have a 06 XL with 20" KMC Addicts wrapped in a set of perelli scorpion STRs (all from the PO) on but I want to swap over to 33" terra grapplers. I wish I could sell the 20" rims and get a set of 17" or 18" rims but I have little money and I would rather catch up on maintenance that was skipped. My questions are:

1. Would I need to modify the suspension at all, or install a leveling kit and how much lift be required?
2. I mainly rid motorcycles and having to deal with offset and backspacing is very new to me so will I need to pull off one of my rims and get measuring to figure out if I can mount the TGs?
3. What sized tires will I need (in the xxx/xxRxx format) or is there a simpler way to go about choosing them?
4. Would it make sense to purchase a 5th rim and tire to replace the spare? (Center cap not withstanding and scratches don't bother me)
5. I see that there are leveling kits made out of different materials, not just metal) is there any benefit to certain materials?
6. Lastly will there be any rubbing if I don't level the front end?

Thanks for your help and I'm sure some, if not all, the questions are simple but This is my first truck so I would rather do it right the first time.

 

assuming you are 4x2 from your sig...

1. leveling kit yes or no depending on how wide of tire and if you go aftermarket wheel with low offset
2. the factory 20 has a known offset, which is very high, so no, no need to pull off a wheel.
3. 275/60/20 will work best on factory rim and with least rubbing imo, but there are other sizes http://www.nittotire.com/Tire/terragrappler#size
4. no, especially since you say youre short on change
5. autospring is usually the company to go with
6. hard to say on the rubbing without knowing size of tire and if you go aftermarket wheels. my set up rubs a little but i can live with it. do you want zero rubbing?

just a little heads up you could probably trade your 20s for someones 18s plus cash. or hop on craigslist. i just picked up a set of mint 18 inch fx4 wheels with caps and lugs for 100 bucks

 

Thanks for the reply, I already have a set of 20" KMC Addicts that the PO installed, and the spare is a 17" OEM.