If a wheel slippage problem is something that you need to kill-off, then Halo's all new Butch-washers with their sharp cut teeth, force multiplying design and butch, non-bending, heat treated, 4mm thick steel bodies are the 'no messin' about' answer for you..
Halo Butch Design Functions:
Force multiplier design increases the force applied by 30%.
(3mm grip face Vs 4.5mm nut face.)
Smooth Nut face reduces tightening torque friction. 
Sharp cut teeth 'bite' into any surface to provide maximum grip.
Tech:
4mm thick hardened Cr-Mo steel body (resists bending.) 
10.2mm clearance hole (fits 3/8" and 10mm axles) 
20mm outer diameter grip-face (fits into most dropouts.) 
Black Oxide finish (suits most applications)