3.75" is gonna be close with the calipers, best I can tell you is test fit all four with the size tires you're gonna run on the ST to make sure. Most say to go 4" backspacing but you should be good.
My 97 TJ steel wheels jammed against the rear calipers on my 03 ST, so I bought some new steel wheel rims for my winter tires. My friend said he ran into that problem before and he got his grinder out and knocked a bit off of his calipers instead of buying wheel spacers. :argue: