This can be confusing. Mickey Thompson has several flavors of 10.5W slicks:
28x10.5W tread width 10.9"
29x10.5W 11.2
31.25x10.5W 10.8
33x10.5W 11.2
Section widths vary but can be adjusted by using a narrower rim than suggested by the tire manufacturer. This comes as a caveat - cupping of the tread with less contact patch. There's nothing wrong with a non-W slick but run a 10-12 rim width with the the tallest tire having the tread width you desire. A 29" diameter tire with 10" tread with has a larger contact patch than a 28" diameter slick with the same tread width. Same applies for a W tire. The NHRA stockers run the tallest 9" wide slick they can fit for this very reason. You need to do the math for tire diameter that matches your desired maximum safe piston speed and finish line RPM. Rim offset for clearance combined with section width is at your discretion. Also a stiff sidewall is probably best for a heavy or high horsepower ride. I run a 31.25x10.5W non stiff in 2675# Coronet, on a 12" wide wheel,but only to meet the 10.5 NSS tire tread limit. In all honesty I don't need more tire. It runs 9.30's with a very mild engine. Don't over tire - it's just more unsprung weight. If l you find that a regular 10.5 or 10.5W is too soft, you can always add tubes rather than go to a stiff tire.