Wolves and Coyotes are very similar to one another and are about the same size. So mating between the two would be about the same as if it were 2 wolves mating or 2 coyotes mating.
The male of either species will mate with the female of the other species as if she was the same species as the male. There is a slight difference between the two species when the tie occurs. In the case of a male wolf/female coyote, the male's knot is slightly larger than what the female coyote is used to which can cause some minor pain upon removal*. But in the case of a male coyote/female wolf couple, there is no real difference to the female between a wolf and a coyote. In either case, the couple will often mate for 30 to 45 minutes however they may mate for as long as 90 minutes.
About 2 months later, the female will give birth to up to 12 pups (both wolf and coyote). General ranges 3 to 6 for a female wolf, and 6 to 12 for a female coyote.