After showing encouraging one-lap pace in Fuji pre-season testing and in qualifying for last month's opening race at the same track, Mugen's Red Bull-backed Honda NSX-GT was one of several Yokohama runners to encounter tyre trouble in the curtain-raiser.
It's understood this prompted Yokohama, which also supplies the Bandoh Toyota and Kondo Nissan in the GT500 class, to bring a stiffer construction tyre to last weekend's second round.
However, the Mugen car shared by Sasahara and Hideki Mutoh struggled for pace and ended up down in 10th, one minute behind the winning Bridgestone-shod Real Racing Honda.
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Asked if Yokohama's strong pace in the Suzuka tyre test in July was any cause for optimism, Sasahara replied: "In the tyre test we were fast in the dry over one lap, but maybe just for one lap. In the race run there is clearly a problem.
"Hopefully we can do a better result in Suzuka, but we just have to see where we are and Bridgestone will be strong."
Sasahara said Honda's stronger performance in general in the second Fuji race was down to having long-run data to work with from the opener, which was lacking after pre-season testing.
"I think all the Hondas found something better set-up wise," said the Mugen driver. "We always did short runs and couldn’t do many long runs [in testing], so before the first round we knew that long runs were a problem. We couldn’t protect the tyres.
"In the end you could see #17 and #8 [Real Racing and ARTA cars] improved significantly. We also found a good set-up that’s kind of helping, but the tyre is still a really difficult factor."
Yokohama's last SUPER GT win came back at Motegi in 2016 with Kondo pair Daiki Sasaki and Masataka Yanagida, one of three triumphs for the tyre maker that season.
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