Technical Artillery Wheels

I bought an original 40 Chev pickup, it has 15 inch Artillery wheels. I dont know much about old trucks, it seems that 15 inch wheels might not have been popular in 40. My manuel shows lots of 16 and 17 inch truck wheels, 15 inch is just added to the bottom of the listing.
Anyone have a little more info. Thanks, Rick

 

From '35 - '42 on Chevrolets they were optional on 1/2 tons, standard on what they called their 3/4 ton which was nothing more than a 10'' longer ch***is. 15'' wheels are a "heavy duty" option, & tire sizes are odd sounding today ... like 7 X 15, & 15 Commercial.