Nah, it's all dry tarmac races. The issue is that Retro Sports Cars in B class means you don't have a whole lot of overhead for upgrading since most are high C/low B already. If you don't upgrade the tires then you lose out in the corners thanks to crappy 30+ year old rubber, but if you do upgrade them then you burn up most of your PI cap and can't do much elsewhere. That's likely why everyone is recommending the Trueno, since it would be fairly low PI at stock and allow for more extreme tuning.
The R33 Skyline I used was mostly topped out after sports tires, race brakes and a clutch upgrade, so I just concentrated on keeping my speed up through corners and using the car's weight to make sure the AI that fell behind stayed behind. My team never did catch the first or second place cars in the two that we won, but with all of us taking up the next six spots it didn't really matter.