CraigM - I've requested them mainly because of the difference in off-sets between all the rims. If you measure between the TOP or Tamiya rims, they will make the car the most narrow but as you work through different rims and especially into the foam tire rims I found that you would need as narrow as a 4-3.5mm hex to keep the overall width the same. Of course in the rear this is ok but in the front it can create some clearance issues with the rim spokes on the suspension arm. I think they will make a 4mm hex at some point but I think that will wait until we are 100% that there won't be a clearance issue...