I’m doing the stories in FH5 and have come to Speed Icons.
It’s rather dificult to complete these stories when the tires mounted are Offroad - even on the Ferrari F40 and the whole mission is to drive on Tarmac.
The episode with the Nissan Skyline with wide body kit, twin turbo and RWD is also completely impossible to complete with Offroad Tires
I think this is a general problem across all Stories , that Offroad tires are mounted on most / all cars in stories.
Are you sure they’re offroad tires and not rally?
“Impossible” is overstating your problem I think since many have completed this story. My guess is maybe turn down the difficulty?
EDIT: Yeah, I do see they appear to be offroad tires. 
Which episode is that? All I see are episodes with:
1-Toyota Supra
2-Napeir Railton
3-'32 Ford Deluxe Coupe
4-Dodge Dart
5-Ferrari F40
6-Toyota Supra
7-Hennesey Venom
8-Rimac Nevera
If you do the stories in winter season it changes the tyres, giving the cars a lower PI. Try it now.
Hi and thanks for looking into it and confirming that the tires was all Offroad.
I’ll try again in summer season 