It depends on the model of pump set. The Spart Pump Set and C-Pump Set bar is a custom width, so cannot fit standard plates. Our Orbit Pump Set has a standard width bar so it can fix extra standard plates. However, it is not common that people will opt to add additional weight plates, as pump sets are usually used for low weight, high repetition training vs heavy weight training. For heavyweight training, you are better of using 6’ Deluxe Barbell with standard plates or pancake plates.