Wood beams for pallet rack wire decking
I think I see what you want to do.  You want to run two joists 11' across your garage 42" apart, and use 42" x 46" pallet rack for the floor rather than the usual plywood, and you're trying to determine what size joist to use.  

The usual span tables are not quite right to answer this question.  The span tables that are published are based on the length of the span, the size of the joist, the type of wood, the live and dead 
(uniform) loads on the floor, the acceptable deflection, and the spacing between joists.   

Right off the bat, the span tables won't list spans for 42" spacing.  They make tables for the commonly used values, 12", 16", and 24" on-centers spacing, but not for arbitrary values like 42".  

You could take this to an engineer, they can do the calculations that are used to generate the span tables, so they can handle the oddball 42" spacing.  

The span tables are also built around uniform live and dead loads per square foot, so that will work a little different.  

You might be tempted to guess that since you're less-than-doubling the 24" spacing to 42", maybe if you doubled up the joists, you'd be OK.  So if the span tables say you're good at 24" spacing with 2x10 joists, maybe you'd be OK with doubled 2x10's at double that spacing.  It's a reasonable guess but it would be an experiment.  

Of course you could just use three joists - the outer two spaced 42" and the third halfway between them - then you are at 21" OC and if you use the 24" span tables you should be OK.  The pallet rack wire grid would still fit over the joists.  

It's still a bit of an experiment, I don't know if there's anything problematic about wire grid on wood joist supports that are not immediately apparent - it's not an accepted construction method and it's not anything the manufacturer intended.  

I don't like the idea that the wire grids are not attached to the joists, but I couldn't point to a specific hazard where they would lift up either.  

edit:  this very interesting link was posted in the comments 

Wood Beam Calculator

That calculator does allow you to enter 42" spacing.  The only part that seemed a little wonky is the Grade selection, it was only with the Grade "misc" selected that doubled 2x10's came up as an acceptable beam:  



Keep in mind that if you just use plywood and standard joist spacing, you can turn this experiment into a nice boring, safe, standard, business as usual construction project.  You'll save money, gain some peace of mind, and when it comes time to sell the house, you won't have to have a long discussion with the home inspector and prospective buyer.