@big house
i bought some FG 18mm square wheel adapters which are 9,5mm wide (part nummer FG6107 i think). They fit perfectly onto the 1:8 truggy axles as they have a 8mm bore and can be tightened onto the axles with 2 6mm grub screws (i never lost one adapter while driving). You can find square wheel adapters with more width (i chose the narrowest i could find). You only have to make sure they feature a 18mm square and have an 8mm bore (i think 8mm axles are common to most 1:8 truggys or buggys).
I'm using a screw and a washer to keep the wheel onto the wheel adapter as the truggy axle comes with a thread. I realy thought i will loose my wheels while driving but this never happened.