Brush the corn with olive oil and place on the grill. Cook, turning occasionally, until charred and tender, about 10 minutes.
Remove the corn from the grill and let cool slightly. Cut the kernels off the cob and place in a mixing bowl.
Warm the tortillas on the grill for about 30 seconds on each side.
Assemble the tacos by placing a generous amount of grilled corn on each tortilla. Top with shredded red cabbage, chopped cilantro, and crumbled cotija cheese. Serve with lime wedges.