My garage is on the backside of the utility room where the dryer is. SInce the dryer is gas, the 220 (actually 238V at my place) plug was not used. I opened up the wall on the garage side, pulled the wires through (they were 8 ga unfortunately), and installed a plug on the the garage side. I just matched the socket up with the welder plug. Technically the welder can draw above the 30amps of the circuit, but since I'm not building a battleship, I've never tripped it.
On the same circuit, I also ran another socket for the compressor which can draw 8-9 amps. I have sice learned this is not to code, and the plan is to take it out and have the garage wiring redone by a real electrician, with a subpanel, multiple 220 outlets, and more capacity. Still, It works, I'm just careful with my use patterns.