The ET48.3 requires the upgraded "+2" mm hexes that Tekno offers to allow clearance for Im certain standard and 1/2" offset Proline 3.8 wheels/tires. The MT has the hexes included in the kit which is why basically any 17mm wheels fit, but I wanted to try the +2 hexes on my EB48.4 a couple years ago for a track day and because I had originally built the ET48.3 with the wider hexes I had never tried different wheels with the stock ones, so thats when I found out that pretty much only the standard track focused 4" truggy race wheels work on the stock hubs, and none of the 3 different styles of standard or 1/2" offset Proline 3.8's or 2 other 3.8 wheel sets I had but dont remember the brand spun freely as the recess where the 17mm hex fits is too deep so the wheels all rubbed on the steering blocks and rear uprights. I did order up a set of the first generation low profile belted Sweep all-terrain tires/wheels which have a 1/4" offset and they would work without the wider hexes, however they have since changed all of their sets to a 1/2" offset so I cant say for sure if the newer versions would still fit. They have been a great setup for when Im running any of my trucks ie truggies on-road or have them set up for higher speeds as the tires dont balloon even a slight amount as they pretty much feel like they are nearly solid rubber. The downside is the tires send every bump to the suspension and if you run them on really hard and rough surfaces its not unusual to crack a wheel from the inner tire bead moat of the way across to where the spokes meet the rim. Happened to me twice, but some tire glue has kept them running strong now for almost 2.5 years, still having over 1/2 treadlife left too...