Slaters do the wheelsets in 16.5mm gauge, catalogue number 32512HUD, see https://slatersplastikard.com/wheels/32mmNGWheels.php
if you cannot manage to push them in on the axles. I am not sure if the 1/32 wheelsets have shouldered axles (their O gauge wheels do), so replacing them may be the only option if that is the case.
Two ways of narrowing the gauge come to mind if they are plain axles.
The bodger in me would measure the distance between the wheel face and the axle end, then find two bits of scrap brass that are thicker than that distance plus the distance the wheel needs to be move in along the axle. Drill a hole in each piece of brass to take the axle, then reduce the thickness of the brass to match the distance the wheel needs to be from the axle end. Place one piece of brass on each end of the axle, place gently in the vice (you may need three hands) and check everything is square on to the vice jaws, then carefully squeeze the wheels along the axle. Don't squeeze too hard otherwise you will end up with a banana shaped axle - been there, done that.........
If you have a pillar drill with a depth stop you can use this to push the wheel along the axle, one end of the wheel set at a time. Grip the axle loosely in the chuck with the uppermost wheel face up against the jaws and rest the lower end of the axle on top of the machine vice. The axle has to be able to move in the chuck with finger pressure, but not be a sloppy fit otherwise the wheel may be pushed off square and end up wobbling. Carefully press down on the upper wheel with the chuck (small steps are best) and keep checking the distance from the axle end to the face of the wheel. When this is OK set the depth stop using the first altered wheel in the chuck as a guide so that the amount of movement can be replicated for all of the other wheels.
Don't forget to check the back to back measurement on each set of wheels that you alter, as it is too easy to overlook then you end up with a wagon that climbs over the first set of points it comes to. Ask me how I know.............
Hope that helps.