I was going through some books for engineering and trailer build guidelines. Straight trailer design axel placement for 60% front/40% rear load balance gives good tounge weight and good tow balance. Load front heavy to prevent fishtail.
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I been towing a trailer for years, hardly noticeable when traveling at speed, and only noticeable in starts and stops. In a way it appears to give better balance to your bike when traveling. Make sure when loading, that you evenly distribute the weight in the trailer, heaviest stuff over the axle..

in Australia it is recomended to have 5- 10% ball weight
we manufacture trailers and rule of thumb is to have the axle1/2" back from centre for every 12 " of body length
But all comes back to how load

How much difference does the wheel size make to the ride of the trailer?

I see some, like the Harbor Freight trailer with little 8" wheels, and then many people with 9" or 12" wheels.

also check rating on towbar/hitch
in Australia they have to have a rating on it giving max ball weight and max trailer weight

i have 10" wheels on ours
tyre pressure is very important
it tows great and is no prob
the bigger the wheels the less stable as gets higher off ground

with the small wheels check rating of tyres

Changes the way you ride, and the way everyone rides who is with you. Though convenient, curves must be taken slower, mountain curves are annoying, even on the straightaway riding is slower. The worst trip I ever had was with another person who had a trailer, and it was very small. Spent two weeks poking along the roads, riding through curves and driving as if we were in a car. Straight up and no lean. Yecch. If you get a trailer, know you change your ride.

if sitting on speed limit it makes no difference even thru corners
altho im not a boy racer
loaded right it is only braking it affects

lOAD RATING IS IMPORTANT BUT MOST OF ALL IS SPEED RATE OF BEARINGS. Some small tire wheel assemblies are not made for highway speeds such as wheelbarows utility carts. The smaller the tire the faster the rotation and the more bearing, lubrication and the balance or tire construction for highway speeds add up. A weight saving idea is rubber torsion axel assemblies that would replace the axel tube, springs and spring mounts. They are bolt on and cost is about the same to slightly cheaper than spring assemblies but a lot easier to assemble.

over here the rubber axle is expensive(about 2 1/2 times that of a spring and axle.) I pesonally have a single 8mm slipper leaf spring and works fine
10" wheels go st8 on a std trailer hub so bearing rating is fine

I have been thinking about getting a trailer. My main concern is will this hurt the motor or transmission on my bike. I have a 2005 Road Glide with 104,000 miles on it.

I hear that Harley does not like it.  Will invalidate your warranty.  I pull one and feel it is much better than piling things high on the bike.  I have not had any bad issues and hardly know it is there except the fuel milage goes down.  Mine is a very big, cheap one.  Wind does not seem to bother it much.  I have had it in South Dakota with some strong winds and I don't think I was bothered anymore than others with me without a trailer.

Jeff
it wont be as bad than loading the back

Hey Lucky, you ever get that trailer built?  Pictures?

we manufacture trailers and I tow a trailer behind Viagra .Standards in Australia state 5-10% ball weight . Most towbars /hitches will have on there what manufacturer of them stipulate again 5-10%

I don't know if this forum is still active but I've been pulling both cargo and camper trailers for about ten years now and have seen some good and not so good advice on here. Experience is still the best teacher...

To JeffHD asking about hurting the engine and trans... I've got a '05 Glide with the same mileage as yours and after at least 25,000 miles pulling a fully loaded trailer and some times riding two up, it hasn't hurt a thing. It hurts gas mileage and back tires if it's not loaded right but it hasn't hurt the bike yet. Still has the original clutch in it to.

I have been thinking of building a trailer... I would get a lot more riding time in if I had a trailer that could hold two guitars, and some extra gear... it would eliminate the need of taking a car to gigs

I have towed a trailer back and forth across the country, and can say it was the best investment I have made. As for the original question about handling - let me tell you having the weight in the trailer vs up high on a luggage rack is MUCH easier.

To bring up an old topic, just got back from a trip to GNP in MT and area.  My buddy and wife had a trailer.  The cooler full of beer and meat to grill finally sold me on the whole package.

Talking to guys on the road, there seemed to be a consensus on the tires.  Many seemed to prefer the larger thinner tires for less drag.  They said it pulled better and did little to the bikes efficiency.

Any thoughts or experiences on this topic?

Kind of what I heard from most I talked to. The taller tires also make for a lot less bouncing around.

Not sure if you have been looking at used trailers, but their are some killer deals out there right now, at least in our area.

You are subject to different challenges on the hghway if you tow a trailer. Hauling a substantial amount of anything takes time, fuel, and effort. Whenever you have stuff to haul, deciding how to haul it could be a calculation that involves considerable cost. Article source: Doing the math of towing a trailer.
 

My granddad and i have rode motorcycles together for 20 years now, when i was younger and rode with him he would pull his trailer and it always seemed fine as a passenger, but when i was older and fallowing him during a ride and he had his trailer, i can remember seeing him go around a curve a little fast and the trailer pulled him to the outside in a bouncing fasion. and i can remember him saying about stopping your bike with a heavy trailer, it will push your bike through an intersection if you are not paying attention.....

I'm two years late on this question,alls I know is don't forget it s behind you when you overtake.