Question about adding wheel extenders to the rear of my mbx-5 on road project

[suicideneil]

I believe the wider rear tyres is down to a traction related issue (same with overpowered 1:1 cars whether 2 or 4 wheel drive). Offset is definately to do with stabilty- narrower will turn better, wider is more stable, all other things being equal (servo, tyres, steering throw).