Hey there how's it going? The 4.5" kit will clear up to a 35x12.50 tire on a 17" rim or larger with 5.75" backspacing or less. Stock rims are compatible with this kit as well. As far as rear heights we offer either a 1.5" rear coil spacers or we have a 3" kit. It really comes down to 2 things: how you want your truck to sit and/or how much rake it has from the factory. None of these trucks have the same amount of rake so depending on how much it's got will determine how much lift you need in the rear. Say you only have 1.5" of rake then I would recommend running the 3" kit in the rear to make it level. Now say you have 3" of rake then I would recommend the 1.5" spacers to make it level. If you are somewhere in between that you will need to determine if you want it to sit rear tall or rear low. So it just depends on the truck itself or how you prefer it to sit. My experience with these trucks especially from feedback on the forum here is that people tend to go with taller in the rear which totally contradicts how people out in california like their trucks haha. I always like to recommend measuring how much rake your truck has and then make the decision on the rear height from there. Please let me know if you have any questions, need part numbers or need a referral to a place to purchase your parts. Thanks and have a good one -- Sean