I moved from a C-rated 275/70R17 AT/3 to an E-rated 305/70R17 AT/3 XLT. I only have a few hundred miles on the XLTs, but they are only marginally stiffer than the C-load range AT/3s. I also cranked my torsion bars a bit, so may not be a really fair comparison. However, they are not as still...