Your question is too vague to answer with any certainty of accuracy. My recommendation is to get the tag number off the axle and call the manufacturer. You can get "guestimations" all day on here but I'd be willing to bet you can get an accurate answer from someone who knows in less than 30 minutes on the phone. Something as simple as wall thickness on the main tube could affect the weight drastically if you want any kind of accuracy.
I'll guess #625. :hehe: