The LL is deeply flawed because of driver talent and tire grip. They would need to put all the cars on similar tires and have someone like Randy Pobst drive them same day same conditions to even get close. We were told by a Kuhmo representative that the Viper OEM Kuhmo's should have a wear rating of 60 not 200.
Hoosier A6-A7 have a TW of 40 and are 3-4 seconds faster per lap than a Michelin Ultra performance summer tire.
I use to think the same but not so much anymore since more often than not, sportscars now have bespoke versions of a given tire model with specific design, construction, and compound bespoke to the particular car.
If two cars turn the same time on their own bespoke tires (say a MPSC2 & Trofeo R), but you then put them both on the bespoke MPSC2 and one car is a second faster than the other, but then say the opposite is true if both cars were on Trofeo Rs, what would you learn?
UTQG is a made up joke. Any tire mfg can use any UTQG treadwear number on any tire they like to convey to the consumer that this tire lasts longer, or that tire is stickier, or to make a "cheater" tire for a specific autocross, time trial, or club race category. There is no standard and you really shouldn't take anything away from looking at that rating.
FWIW, Ford stated their bespoke MPSC2 is roughly as fast as the Hoosier R6.
EDIT - I like this quote:
"Uniform Tire Quality Grade (UTQG)
– An arbitrary number originally developed to help consumers with a numerical value that represents the treadwear, traction, and temperature capabilities of the tire. Since the Department Of Transportation (DOT) does not test the tires and it’s up to the tire manufacturer to come up with the value, tire manufacturers set these numbers based on how they perceive the customer will understand how the tire will perform, or to meet a random number/standard that a racing series might restrict, to have a softer faster tire as an advantage. Because of all of this, UTQG is USELESS."