yes, they can plug it without removing the wheel. the guy that fixed mine left the wheel on. however, the repair is easier to do with the wheel off. pretty much any roadside repair company should carry tire plugs. it can't hurt to carry a repair kit and needlenose pliers in your car even though you would not attempt the repair yourself (i.e. a friend, family member, or another motorist is willing to help). even though the procedure is simple enough it can take a lot of work to get the tools and plug to work through the rubber and steel belts. it can also be difficult to remove road hazards such as screws from the tire. i've repaired tires for both our other cars recently with my repair kit and you really have to push hard to get the cleaning tool and then the plug tool through the tire.

since the tire is already flat, attempting to plug it won't cause any immediate additional damage. you can always take the car in later to have the tire inspected and patched from the inside. i suppose there can be some implications to the tire warranty, but original equipment tires don't usually come with any warranty. but it's still a far superior method of repair to using the tirefit sealant. WARNING: if used properly the tirefit system may ruin the tire valve and pressure sensor. if the hole isn't too big the plug will work just fine for any holes in the tread. the repair kit manufacturers and some technicians suggest that a tire plug is not a permanent fix. however, i've had numerous tires plugged and none have ever failed. one thing that can happen, according to the pros, is that moisture could get into the hole that was plugged and cause corrosion of the steel belts resulting in tread separation.