Bicycle Mechanics - Hub Width Effect on Wheel Strenght

I have a steel touring frame which will accommodate either 135mm rear hub width or 130mm hubs. I plan on getting some 700c wheels, dyad rims, 2.0mm straight spokes, and 40 spokes per wheel.

Is there any strength advantage in going with a road width hub (130mm) vs a MTB Hub (135mm)? Is there a structural advantage to having that extra width? Also a related question, are MTB hubs generally stronger than road hubs?

I have several choices of Hubs--I can get Velocity hubs (I hear they are actually IRO brand) or spend the extra and get Phil Wood hubs. Also, it I decide to go with just 36 spokes per wheel, I can get either Ultegra or XT hubs.

The use will be loaded touring carrying 300 pounds, rider and load. Any comments on my choices?

I can't imagine you'd gain any significant strength from those extra 5 mm. But I know nothing.

The combination of the PW hub on either 40 spoke rim is going to give you an incredibly nice wheel that should take everything you can throw at it... there is nothing better than a Phil Wood's hub.

There is also nothing wrong with Ultegra or XT hubs and a well built 36 spoke wheel is also going to be very very good but for a 300 pound load I would choose option A.

The difference in hub strength is going to be pretty negligible.

The wider the hub,the more balanced the spoke tension.If you can get a 135 hub in your frame,get it.Also use butted spokes as opposed to staight spokes.

The strength difference isn't in the hub. Both widths are more than strong enough. The advantage to a 135 mm hub is that the resulting wheel will require less dish than one built on a 130 mm hub so the overall wheel will be a bit stronger.