check the diameter of the hex nut that the rims go onto. they are normally 17mm or 19 mm. you will normally get an option when buying. as long as the hex on the rims and the hex on the wheel nuts are the same they will fit.

i go to the ofna website who give you quite a large selection. other than that i go to www.three5models.com or www.apexmodels.co.uk.

If you are unsure go back to the LHS you bought it from.l I know that STO racing sell the axis so they would be able to help.