New bike wheels dont sit in dropouts perfectly, are washers safe to use? I recently upgraded my road bike from Vision Team 30's to Mavic Ksyrium Elite UST wheels,  However once I got the wheels and put them on, the rear wheel seems to rub on the brake hardware when riding.  When I put the bike on a hanger and spin the wheel, it seems fine, but every time I ride, I can feel resistance, as if I'm riding with the brake slightly engaged.  I messed around with the quick release and found out that even with it tightened as much as humanly possible, The rear axles seem to almost be a little too short, and I think this causes them to sit slightly loose in the rear dropouts, despite the skewer being tightened all the way.  I tried using the QR skewer that came with the wheels, but it is worse than the ones that came with the Vision wheels, so I've been using them, but still have a bit of play with the rear wheel.  From the looks of it, I could throw a washer in between the axle and the frame to have it sit snug, but I'm wondering if this is safe or not? By my estimates, the gap with the new wheels is maybe 1-2mm, just about the size of a washer.  

I was under the impression (not knowing much about road bikes) that all wheel axles had the same width, is this not true?

Update: photo showing washer and problem area:


It seems the washer works great.  No more wobble in the wheel, no more rubbing.
could it simply be that the new rim is a few millimeters wider and the brakes are making contact because of that? If the wheel is seated into the dropout all the way, the quick release will have enough force to fully clamp the frame to the hub securely. Check by unclamping the qr, putting some body weight on the saddle with a shoulder and reclamp the qr. Beyond that, mattnz's suggestion above is possible. The whole hub assembly/bearings might be too tight or too loose, which is an easy fix.