Currently, surface particle effects will only emit from either the front or back wheels of a vehicle, depending on the direction in which it is moving.
It would be great if we had the option to make particles emit from all 4 wheels at the same time. This would allow us to craft better / unique dust effects, especially since we are now able to define custom dust / surfaces in our terrains without overriding vanilla vehicle classes (rightDustEffects, leftDustEffects, etc see here).
However, it would not be a good idea to generally enable particles for all 4 wheels, as this would 1. double the particle counts (potential performance issue), and 2. all vanilla effects are made with 2 wheels in mind, thus might not look "good" anymore.
I'm not really sure how this issue could be resolved - maybe a flag in the effect itself which tells the game when it is ok to use all 4 wheels and when not?