Nutted rear wheels can be torqued anywhere from 260 - 390 inch pounds / 21-32 foot pounds as per Park's tables on such things.

After you turn wrenches for a very long time your sense of how much torque gets very acute and when I have checked things like how much torque I have put into a rear wheel nut it has always been within the advised range.

I work on a lot of old Raleigh 3 speeds with Sturmey Archer hubs and because the nuts are very soft and easy to strip you do need less torque and this is why their lock washers are so very good.

I am not a very big or imposing guy but have had people come back to me asking how to get their wheel nuts off after I have installed them...

With a fixed gear the nut is only part of the equation as a really good lock washer is also required to keep the wheel from slipping... you would be surprised at how much torque an average human being can put to the back wheel.

I do some really intense climbing where the short burst output is the same as a track sprinter's and have to know my wheels are not going to budge.