Here are several ways to mount Speed Passion LM1 front tires/wheels, #SP000990, on the front of a WGT or 1/10 scale pan car. Choose whatever method you prefer, or whatever method uses the parts you already have in the parts box!
The first method is pretty low-tech and quite obvious, but works okay. You'll need four unflanged bearings with 3/8" OD. The ID should be whatever fits the axles on your car, 1/8" or 3/16". You'll also need some brass shim stock, 0.010" thick. (I used K&S #5251.) The 3/16" ID bearings are thinner than the 1/8" ID bearings, so if you use these, insert one 6mm ID x 10mm OD washer, about 0.5mm to 0.8mm thick (Duratrax #DTXC9767), into each opening in the wheel before inserting the bearings to take up the extra space.
Cut the brass shim stock 1/8" wide and about 1.15" long (good scissors work nicely for this). Form the shim around the bearing OD, then insert the shim (after the washer, if necessary) into the wheel. Then use a round, flat-faced tool to press the bearing into place. The tool should bear against the outer race of the bearing. I used a socket wrench.
When inserting the shim in the wheel on the side opposite one that has the bearing already inserted, line up the gap in the shim to the same place as the first to reduce the possibility of wobble. (The rims wobble enough as is!)
After doing all four bearings, mount the wheels to the car in the usual manner.
The SP wheels will give an extra 1.5mm offset per side, or a width increase of 3mm across the car, compared to BSR WGT tires.
Bearings, 1/8" ID x 3/8" OD x 5/32" Width:
Bearings, 3/16" ID x 3/8" OD x 1/8" Width:
and Washers, 6mm ID x 10mm OD:
Here is a more elegant way to mount the wheels on 1/8" axles:
You'll need four bearings, 5mm ID x 10mm OD by 4mm Width. These will need a reducer to match the ID to the axle. I used a nylon spacer, 3.2mm ID x 5mm OD x 11mm long (Harwin R30-6701194).
Place the spacer inside the wheel, with a bearing on each side. Now use a long 4-40 screw, nut, and washer placed through the bearings and spacer to press the assembly together inside the wheel. The washer goes under the head of the screw to press against the inner race of the bearing. The nut presses against the inner race of the other bearing. (Use a washer here, too, if the nut is too small.) Tighten the screw and nut to press the assembly together inside the wheel. The bearing edges should line up with the ends of the spacer when finished.
Place a 4-40 washer, about 0.13" ID x .26" OD x 0.020" thick, onto the axle, slide the wheel assembly onto the axle, place another washer on the axle, then install the axle nut. Don't over-torque the nut, or the spacer will compress and bind things up. Just snug will do. The washers provide a surface for the bearing inner races to contact.
Bearings, 5mm ID x 10mm OD by 4mm Width:
Nylon Spacer, 3.2mm ID x 5mm OD x 11mm long:
And finally, the prettiest way to do it! This is just a variation on the previous method, but the standoff is aluminum, which makes it a bit more rugged. The 1/8" axle stubs in the car should be secured with a nut on both ends, since the wheel nut will need to be torqued down firmly to take up the small amount of play between the standoff and the axle.
The bearings must have a 6mm ID, and these types are narrower than the 5mm ID bearings used in the previous example. Place two 6mm ID x 10mm OD x 0.5mm thick washers (Duratrax #DTXC9767) inside each side of the wheel to take up the extra space before installing the bearings. I found that I had to open up the ID of the washers a bit (using a round file or reamer) to keep them from dragging on the standoff.
As in the previous example, two washers are needed on the axle for the bearing inner races to contact, but the washers need a larger OD since the bearing ID is larger. I used 3.2mm ID x 8mm OD x 0.5mm thick washers (Thunder Tiger #PD1966).
Bearings, 6mm ID x 10mm OD by 3mm Width:
Aluminum Spacer, 3.2mm ID x 6mm OD x 11mm long:
Washers, 6mm ID x 10mm OD:
Washers, 3.2mm ID x 8mm OD x 0.5mm thick: