The seven-time MotoGP champion had finished the Sunday morning warm-up in Buriram a promising fourth, but faded almost right away in the race, toiling to an eventual eighth-place finish.
The other works Yamaha of Vinales shadowed leaders Quartararo and Marc Marquez for virtually the entire race, but the Spaniard was unable to recover from dropping ground in the battle in the opening half of the event and had to settle for finishing a second behind in third.
Vinales said he too was stymied by a rear grip problem, and has called on Yamaha to improve matters.
Second place Maverick Vinales, Yamaha Factory Racing
Photo by: Gold and Goose / LAT Images