...
The key, says
Mavic, is the very precise dimensions dictated for both the rims and tires, as well as unusually tight dimensional tolerances for all of the key components — more stringent than what Hutchinson uses for its own tires currently, and with less variance than what
Mavic had previously deemed allowable for its own wheels and tires.
For example,
Mavic says it has historically held its conventional road rim diameter tolerances to 621.95mm +/-0.5mm, but Road UST-compatible models will now vary by only +/-0.35mm; tires are being held to 619.6mm +/-0.2mm. As compared to pre-UST rims, the total variance in rim diameter thus drops a scant 0.3mm, from 1mm down to just 0.7mm. That may sound insignificant, but keep in mind that that small change in rim diameter yields a much bigger difference in rim circumference, and when coupled with the variations in tire bead diameter, can mean the difference between a secure fit and a loose one if any of the components are allowed to stray outside of those parameters....