in the subject of tyres - the more "slick" they are, the better:
so-so ones
Michelin XTE2 365/80/R20 160 K
- thread uneven, cut partially
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best:
Uniroyal R300 365/80/R20 160 K
Matador TH1 385/65/R22,5 160 K
thread even, not cut, roll superbly.
Of course cut and uneven grip better, but the EF is an aim.
If the UNI is underpowered, go down with the tyre profile - that means better torque on tyres and faster gear change [EF up and lighter tyres]
you can also consider skinner tyres for smaller drag.