The Tiagra hub and 8 speed cassette are irrelevant, but yes, it would be a good (and depending on who you are talking to, cool) idea to use a thinner gauge spoke on the non-drive side. My commuter rear wheel uses Competition spokes on the drive side and Revolution spokes on the non-drive side plus an offset rim. IIRC, NDS tension is ~75-80% of DS with this arrangement.

I don't stay up with the various brand names, but if you considering using a thicker spoke on the right than the left, then it makes sense as a way to compensate for the lower tension. I'm a strong believer in butted spokes at the hub end so I use different gauges (thin section) of 14g/xx spokes right and left, or for heavy duty wheels use a 14/13g single butted spoke on the right side and a 14/16g spoke on the left.

Yes but a 105 hub woud be better.

Well, I mean I got the Tiagra hub on sale for $19.10 and the WTB Freedom Ryder 23 rim on sale for $16.88. Even after shipping, it was a pretty good deal.

I like Tiagra hubs. I've got wheels with Tiagra hubs and wheels with Ultegra hubs. When you have them apart to rebuild them, you can see the differences in the parts, but I haven't had to rebuild the Tiagras any more often, and they spin beautifully after the rebuild.

Tiagra is certainly good enough.

You mean straight 14 ga right, butted on the left?,

a budget saver: maybe use 14 0n the right 15 on the left, Plain on both sides?
and 15 on the front ..
Have a 20+ year old 36 spoke wheel set built with straight 15 gage spokes ,
and It's been fine..

.. though it's my occasional sport bike now..

How often do you regrease the hubs? (EDIT: or how many miles I should say)

By the way, I can't remember who uses bees wax for the spokes, but if this person is reading this, do you put bees wax on one side or both sides?

EDIT: So, just to make this clear, straight gauge shorter spokes on the drive side and longer double butted on the non-drive side?

The Beeswax is a vegan thread lube, I use Anti Seize .

that goes on the spoke threads as I insert them into the rim.

touch up Truing goes better..

Tension ratio between the two sides isn't going to change with spoke diameter on one side.

Thinner spokes on the left may be good because they stretch more at a given tension so it takes more rim movement (vertically or laterally) until they go slack and allow the nipples to unscrew or wheel to collapse and windup at their low tension is less.

To get more balanced tension you need to change the bracing angle (most probably by using an offset rim (Velocity, IRD), although heads-in radial and cross-1 drive side lacing will do it (with neither being a good idea in this case)) or use fewer non-drive side spokes (triplet lacing between a 32 hole hub and 24 hole rim with 16 drive side spokes but only 8 non-drive-side would do it).

Straight gauge spokes will cost about $3.50 less a side and have less windup but aren't going to provide a performance advantage and will concentrate the stresses in the elbows.

What is windup?

EDIT: As a matter of fact, would there really be a problem if I did choose straight gauge spokes on both sides and put beeswax on the threads on both sides?

It's hard to say how many miles I put on my hubs before regreasing them as I have a couple of wheelsets that I switch around. I would guess I went about 4000 miles before I did it for the rear hub, but about half that in the front. I used these wheels mostly for commuting, but also for about two dozen very muddy cyclocross races in that time, so they saw some pretty nasty conditions. The original grease was still surprisingly clean. I probably could have gone longer.

Regarding the straight spokes, they make building the wheel a lot easier. Double-butted spokes are both lighter and stronger, but straight spokes will still give you a pretty good wheel. I say this as a very amateur wheel builder. I've built four wheels.

As spokes tighten friction in the thread increases. That means that the turning nipple tries to turn the spoke with it. It's a problem with any screw, but the longer and slender it is the more the screw will begin to twist over it's length. Spokes are about as long and slender a screw as you'll find anywhere, so when you turn the nipple the spoke will twist somewhat until there's enough resistance for the nipple to actually turn with respect to the spoke. You'll feel it as you do some of the final tightening. Greater twist makes it harder to gauge what you're doing when you do final alignment, and makes it harder. The thinner the spoke the greater the amount of twist.

Different builders have tricks to manage twist, which must be removed when the wheel is finished, or the spoke will untwist over time undoing some of your work. Some develop a feel for it, others use some marking technique.

And a little bit of diameter makes a big difference since torsional stiffness is proportional to the 4th power of diameter. A straight 14 gauge (2.0mm) spoke is 1.5X as stiff as a 14/15 (1.8mm) double butted one and 3.2X as stiff a 14/17 (1.5mm)