On October 19th (Mon.), the day after the race of the 2026 AUTOBACS SUPER GT Round 7, the ”AUTOPOLIS GT 3Hours RACE” was run in Oita Prefecture competed by the 11 GT300 class teams, development tests were conducted by the 2027 official tire suppliers. This was the third such development test conducted following the second development tests conducted on August 24th after the Round 5 Suzuka race.
◎ Morning session 9:00～11:00 Weather: cloudy / Track surface/ dry ◎ Afternoon session 13:00～15:00 Weather: cloudy – some light rain / Track surface/ dry
In SUPER GT from the 2027 series the official tire supplier for the GT500 class will be Bridgestone, and for the GT300 class the official tire supplier will be Dunlop. This time, one day development tests for the tires that will be used by the GT300 class teams next season were held in two sessions, a 2-hour session in the morning and another 2-hour session in the afternoon.
For the Round 7 race the day before, both the air temperature and the track surface temperature were higher than expected for mid-October, and for this day’s tests it was warm from morning, although not as warm as the previous day.
The following are the 11 GT300 cars that competed in the tire tests.
No. 9 PACIFIC UMA MUSUME NAC BMW（Yusuke Tomibayashi / Yuta Fujiwara / Rintaro Kubo / Ryohei Sakaguchi） No. 11 GAINER TANAX Z（Ryuichiro Tomita / Kazuki Oki） No. 18 UPGARAGE AMG GT3（Takashi Kobayashi / Kotaro Shimbara） No. 20 SHADE RACING RC F GT3（Katsuyuki Hiranaka / Eijiro Shimizu） No. 22 R’Qs AMG GT3（Masaki Kano / Hisashi Wada / Masaki Jyonai / Yuma Shoji） No. 56 REALIZE NISSAN MECHANIC CHALLENGE GT-R（Joao Paulo de Oliveira / Iori Kimura） No. 60 Syntium LMcorsa LC500 GT（Hiroki Yoshimoto / Shunsuke Kohno） No. 61 SUBARU BRZ R&D SPORT（Takuto Iguchi / Hideki Yamauchi / Shunji Okumoto） No. 62 HELM MOTORSPORTS GT-R（Yuya Hiraki / Reiji Hiraki） No.96 K-tunes RC F GT3 (Morio Nitta / Shinichi Takagi) No. 360 RUNUP × SOL GT-R（Rin Arakawa / Yu Kanamaru / Atsushi Tanaka）
There was a thin layer of clouds overhead for the morning tests and the track surface was dry. The air temperature was 20℃, and the track surface temperature was 25℃ when the tests started at 9:00 AM. All the cars used the same settings they had used the previous day and practiced comparing tires of the different compounds, soft, medium and hard, and by varying the settings they checked the performance of the tires. Also, while going in and out of their pits frequently, the teams completed their own distinct test menus.
As time passed, patches of clear sky began to appear between the clouds, but meanwhile none of the cars suffered any serious accidents, as the tests went on steadily. In this 2-hour session, it was the No. 61 BZR that recorded the fastest time of 1’45.423. The 2nd and 3rd fastest were the No. 11 Z and the No. 62 GT-R.
During the lunch-time brake from 11:00 AM to 1:00 PM, dark clouds spread low in the sky and at times there was light rainfall, but it didn’t have a big effect on the track condition. At the beginning of the session the weather was cloudy and the track dry, while the air temperature was 23℃, and the track temperature was 22℃.
In this session as well, there were no accidents or other trouble, and while some teams conducted long-run tests, other teams made frequent changes in their settings, as each went through their planned test menus.
In this session, the No. 18 AMG’s Shimabara recorded a time of 1’46.501. Following this came the No. 9 M4 and the No. 22 AMG.
○Yusuke Tomibayashi (No. 9 PACIFIC UMA MUSUME NAC BMW)
“In GT300 we were running on Dunlop tires for the first time. In the morning we ran only with the medium compound tires. We adopted a similar set-up to the one we use in the series, and we didn’t change it much. Of course, some further changes are usually necessary as we progress, with good warm-up there is good grip as a control tire. And I suppose the next thing to consider would be the degradation aspect. I use Dunlop tires in the GR86/BRZ races, and I found the grip and degradation characteristics to be very similar.”
○Ryuichiro Tomita (No. 11 GAINER TANAX Z)
“This was our second test since the ones at Fuji. Since we have heard that the tire contents are exactly the same, basically we concentrated on testing to see which compound best fit this course. We tried all three compounds. And I think that the sense of range was indeed as stated, soft, medium and hard, and since the steps between them is large I got the impression that different ones would be suited for the different seasons and courses. I have been running on Dunlop tires for many years, and my impression is that in terms of characteristics, it gives the impression of sacrificing a bit of maximum grip in exchange for superior wear resistance. So, I think that they are good as one-make tires for running through one-stint use without problems.”
○Takashi Kobayashi (No. 18 UPGARAGE AMG GT3W)
“In these tests I was running on Dunlop tires for the first time, and I had heard from other drivers that they felt not much wrong about them, and indeed I found no bad feeling when I actually ran on them. In the morning we used the medium and hard tires, and I felt that there was not going to be much difference between them. Unlike yesterday, today the track surface temperature had gone down, and since as a whole they warmed up well, I got the feeling that next year it will be easy going out on them in the first lap out on the track. Today again we were watching the response to a number of different set-ups, and I felt like it the coming tests as well we should be able to work things out.”
○Katsuyuki Hiranaka (No. 20 SHADE RACING RC F GT3)
“Since this is the first time for me running tests on Dunlop tires, I ran on all three compounds. My impression is that there is a clear difference in performance among the three tire types. Today the air temperature and the track surface temperature didn’t rise very much, and in that sense I felt that it was a temperature range that suited the medium compound tire. I have been running on Dunlop tires for a long time until now, but I think that today’s tires are different. I got the kind of impression I was expecting for running on Dunlop tires for the first time in a while, and this time I found it to be true. Today we didn’t do a long run, and instead we concentrated on measuring fine points like the adjustments in the tire’s internal pressure. So, these were good tests for getting to know the qualities of the Dunlop tires.”
○Hisashi Wada (No. 22 R’Qs AMG GT3)
“Today we started out with the medium tires, and I found that they warmed up quicker I than expected, and there was an impression of softness. So, I was able to warm them up on the first lap. That was definitely my strongest impression. After that, once the target internal pressure is found, I believe that there won’t be much discrepancy in the under and over settings. However, I got the impression that the medium tires are a bit too soft for conditions like today.”
○Iori Kimura (No. 56 REALIZE NISSAN MECHANIC CHALLENGE GT-R)
“These were the first tests I have run on Dunlop tires. I listened to information from drivers who had participated in tests on GT3 cars, and they said there were no problems at all, but compared to the tires I always use in SUPER GT, I got the impression that there was more difference in the balance than I had expected. So, for my first run on them it was difficult to get a clear impression, and so I haven’t gotten a clear grasp for the feeling of the tires. I had been hearing comments from everyone that, “You rather quickly get a feeling that they are good to drive”, but we got an impression that was a bit different. We tested all three compounds, but we haven’t really gotten to a clear answer. Since this time, it is tire tests, rather than working on the car settings we will be evaluating the tires, and from this we want to think about various things.”
○Hiroki Yoshimoto (No .60 Syntium LMcorsa LC500 GT)
“This is my third time entering tests like this. There were tires with three different compounds and I tried them all. For the hard tire test the air temperature had gone down so it felt like it took a very long time to warm up the tires, but the feeling of grip was close in ways to the medium tires, and I got a good impression from that. In terms of the tire character, it functioned very well in the low-load areas, but with our car (a GT300 regulation car) in the high-load places (the first corner at Suzuka, the 100R turn at Autopolis, on Downhill or last turns) I wanted to feel more stiffness. I wish they would bring it closer to the character of a car like ours. We came to the tests before adding any Success Weight, but I think the basic character was the same. After this, we will work on the compounds and check them out in longer tests.”
○Hideki Yamauchi (No. 61 SUBARU BRZ R&D SPORT)
“This is our third test, and again this time our testing focused on making comparative tests of the different compounds. I think that in these conditions at Autopolis today the medium compound tires were the best. Our test menu included making long runs with the different compounds to find their differences, and we think the medium compound fit the conditions best. In the early stages we ran with the tires with the pink Dunlop logo, but this was only for the initial run, and for the remainder of the test, the cars – much like those of the other teams – were equipped with tires intended for next season. Those tires seemed to performed differently on the different circuits. Until now there was always a competition between the different tire makers, which was interesting, and I’m sad that it will not be that way from next year. And since there will no longer be things like the chance to run two stints with a no-tire-change strategy, we also have a feeling that it will be better for us.”
○Reiji Hiraki (No. 62 HELM MOTORSPORTS GT-R)
“This is our second time running on Dunlop tires. Today we compared driving on tires with three different compounds, and we worked with a test menu in which we tested them in both attacks and long runs all in one day. Perhaps the Autopoliis circuit has its own track surface characteristics, and we felt that each of the different compound tires clearly had places where they performed well or didn’t, and when imagining being in a race we got the impression that it would be difficult to decide on. We feel that it is going to take a bit more time to grasp how to manage the changeable internal pressure, and the best machine set-up that brings out the best of the tires’ characteristics.”
○Morio Nitta (No. 96 K-tunes RC F GT3)
“Our car is a type characterized by heavy weight in the front, and we were working with Dunlop until last year, and I think they had a very difficult time, but looking now at the tires for the first time in these tests, I got the impression that the spot was a bit narrow or confined. In these tests we used the car just as it had been in yesterday’s race and we ran on tires of all three compounds. The medium compound tires were a good match, but with the track surface temperature as it was the hard compound tire seems to have something lacking. Our question from here on is how well we can bring the soft tires to fit the settings I think.”
○Yu Kanamaru (No. 360 RUNUP × SOL GT-R)
“In the morning we ran tests only with the medium compound tires. In the afternoon we will compare the differences of all three compounds. As for the first impression running on the medium tires, concerning their character, the impression was one that the character was close to the Pirelli tires (I used until last year in the GT World Challenge Asia competition). It ran the same lap times as in the long stints of yesterday’s (Round 7), so I thought the times weren’t bad. So, I got the impression that it was very fast as a control tire. And so, I think it can be used in a way close to how the tires are used in the GT World Challenge. Also, since the times didn’t drop much in the long runs, it was much better that what I had expected.”
Naoya Kubo Assistant Manager Motorsports Dept. Sumitomo Rubber Industries, Ltd
“Until now we have done what we call tire development tests at Fuji and Suzuka, and from these our policy was to ask for the recommended menus to be employed. This time, we invited teams to participate, and we did not specify the car models. We also left the test program up to the teams, creating conditions that more closely resembled an actual race. Without concern for the problem of tire durability, the grip balance of the soft, medium and hard tires could also be anticipated. Of course, there will be some differences depending on the type of car used. Seeing that Autopolis is a circuit that causes a great deal of wear on tires, recognizing the details of this effect will be a future concern, but at the point where the tests are concluded the fact that there was not very serious gradation or graining apparent was one of the good points. In the tests until now, the majority of the cars had 300mm front tires and 330mm rear tires, but at Suzuka we had the No. 62 GT-R run on front tires of 330mm. As the number of cars with 330mm front tires has increased, we wanted to see the results of their performance. We got feedback saying that compared to 300mm front tires at Suzuka, it was more difficult to achieve a good package, but from the results this time it seems that it is not such a concern. Although there is a possibility that there may be some new cars entering the GT300 class next season, since we will be keeping the tires basically as they are, we believe that it will be a matter of having them adjust their settings to accommodate the tires when they compete. Rather than saying that from next season the control tires will be made to fit the GT3 regulation cars, it is a matter of creating a package that is more robust in terms of the car’s weight distribution and drive train, etc. As a result however, we have gradually come to see that the behavior of the GT3 regulation cars and the GT300 regulation cars are different. As for this fact, we hope that the GTA BoP (Balance of Performance) and other factors achieve a good balance. The three tests until now have been held in dry conditions, and we haven’t had a chance to test with wet tires. It depends on the weather, so it will be a thing of the future.”
