Yeah, I was going to go with the 1.5” collars as I was about 1 1/4” or so low in the front compared to rear. With this in mind I thought the 1.5”ers would be more than enough to level it. Since I’d seen some people were level with the smaller and some were level with the other, I thought to call RPG and he noted that the 1.5” collars raise the front by about 3/4” and the 2.25” collars would raise it by 1 1/4-1 1/2”. He was right. It’s good on my truck. Of note, I’ve seen so many varied measurements from ground to fender flare on this site. Lots of that has to do with all trucks have a little variation truck to truck and also if you don’t have the truck on perfectly level ground, the measurements will be way off.