If you go to the search function, just above your question and put in the word wheels you will get abbot 950+ pages of answers. Of course that won't stop anyone from answering the question again for the 10,000 time.
And NO, it's not a stupid question at all. Especially if you don't know the answer. But that question is asked every week here in one form or the other, so I thought that I'd give you an opportunity to see how search works and get lots of good answers too.
http://www.trains.com/trccs/search/SearchResults.aspx?q=replacement%20trucks&f=&u=
I typed "replacement trucks" in the search box at lower right of this screen, and I got this first page of many dealing with trucks. Wheels would get different results, but just as many from which you can chose the ones that seem closest to your query.
Good luck.
REAL RAILROADS haul goods - most of which are too heavy for commercial trucks - but not all.
'RR TRUCKS' are selected for weight distribution (and handling), such as 'passenger', or 70 ton, 100 ton, etc. (Passenger trucks also pay attention to 'ride' ).
MODEL TRUCKS' main thrust is 'simulation' - if you will. Since model cars are mostly empty, more attention is paid to cost & looks than weight distribution. MOST freight models come with 33" wheels - regardless of what the prototype had.
Put another way, 50% of todays buyers are new and are less concerned with accuracy than CO$T - The 'As long as it stays on the track' types - or what would you rather call it?
(Purchasers of large, or articulated, locomotives whose main concern is minimum radii - generally 18" )-that they can run on).
Metal wheelsets almost always offer better rolling and tracking characteristics than plastic - they are also much more expensive. (Dont forget to check the gauge!)
The next concern is the design of the truck itself (archbar, etc...) the main concern being, was the type of truck you have in use during the period modeled. While ICC rules would restrict certain truck types from interchange traffic, non-interchange traffic might find older, supposedly obsolete, equip. still in use - especially on a shortline/branchline.
George
"And the sons of Pullman porters and the sons of engineers ride their father's magic carpet made of steel..."