TLDR: By default, frictionTread and frictionNonTread in the surface vehicle physics are set too close together on most surfaces (dirt 0.85/0.65, grass 0.57/0.5), so a vehicle's tread value barely changes anything road cars and off-roaders end up feeling the same off-road. Widening that gap (tested by halving frictionNonTread on dirt/grass) makes tread actually matter: the S105 now genuinely struggles off-road while an off-roader doesn't, creating a real fast on road vs capable off-road tradeoff that didn't exist before.

issue:
Found something worth sharing after digging into the tread/frictionNonTread formula (friction = tread × frictionTread + (1-tread) × frictionNonTread). By default, frictionTread and frictionNonTread are set close together on most surfaces (e.g. dirt at 0.85/0.65, grass at 0.57/0.5). Since a vehicle's tread value just interpolates between those two numbers, a road car and an off road vehicle end up landing close to the same friction no matter their tread value, because the two anchor points are so close.

I tested lowering frictionNonTread on dirt and grass, and the difference is huge. The S105 (road car) actually feels like a street car struggling on dirt now, while an off-road vehicle still handles it fine. Before this change there was barely any handling reason to prefer an off-roader over the S105 off-road, it just felt the same but slower. Now there's a real tradeoff: fast but bad off-road versus slower but capable off-road, which is exactly the kind of decision rally and open-world driving should reward.

Suggestion: revisit the default frictionNonTread values across surfaces (especially dirt, grass) and widen the gap from frictionTread. This alone, without any new systems just change ONE value, makes tread meaningfully affect driving and gives road vs off-road vehicles a real identity difference on soft terrain.


Video: Showing vanilla vs edited only non tread value