Wheel Size???? How important?

[rbaxter]

If you ever get a chance to see a jet liners tires take a good look they have huge cracks in them from landing too high of speeds.

Hmmm. Having been an A&P mech. on heavy airplanes for 40 years, before retirement, I can't say I've seen much of that and I've changed several hundred of the big ugly buggers. Most of the wear on airplane tires occurs on landing when the tires have to accelerate from zero to 160 mph or so in a couple of seconds. If you look at the upper sidewall you'll see an R followed by a number: this tells you how many times the tire has been re-capped and I've seen them go to 24. Most main tire failures are from thrown caps and an occasional brake anti-skid failure.

Bob

[TinKicker]

My friend Bud and I did a test with his 4x8 trailer and my 5x10 trailer we put on 14 inch wheels and then 15 inch wheels. we got better milage with the 15 inch tire and wheels combination.

emiller posted this observation on mileage, and since the machinations of my mind are truly an enigma, I immediately smelled the paradox here:
Bigger, heavier tire/wheel = better mileage? Hmmmm. How?
Lemme' throw this out there: all you aviation lovers will recognize that the angle of attack of the body shape of the given tear against the airstream is minutely yet definately changed by the one inch increase in tire height (1/2" axle height increase). Of course, some tears will be more affected than others, just as delta wings compared to "regular" aircraft wings have different performance envelopes.
So, perhaps the flow of air at highway speeds over emiller's friend Bud's trailer (was it actually a tear?) was subtly improved by the addition of the taller wheel/tire combo.
Ideally, we would all have several different sets of wheels and tires of the various sizes so that we could conduct mileage tests on our newly-completed babies before heading out from one coast to the other. Hopefully the better resourced members here can gradually conduct these sort of tests and offer up a handy-dandy comparison chart with the different tear profiles. Mike? Sounds like your call to glory, you CAD-luvin' tear beast, you!
Just food for thought, and I ate too much.
Oh...stuff this down for dessert...the results would of course be variably based on coupler height and tow vehicle type...the backwash would vary from vehicle to vehicle. Yum...burp.

[doug hodder]

Bigger wheels are needed if you think they look better - technical 'reasons' for needing bigger wheels were invented (usually inaccurately) so that guys didn't have to admit it was just vanity....
Andrew

Guilty as charged....I personally think that the correct wheel/tire combo under a tear should give it a pleasing road appearance. All the options aircraft/automotive/small/large, wide etc... don't matter a bit if when it is all said and done... it just doesn't look appropriate. Just my opinion, but entire industries have been built upon this vanity...I'm sure others will have differing opinons. Doug

[Gary and Cheri]

What I would be curious about what would be the result of using low resistance tires found on hybred cars from Toyota or Honda. Would such a tire work with a tear and would it make a difference milage wise as they should pull with less resistance? Also I wonder what affect changing axle/bearing grease to a high quality synthetic might have on milage. Also changing from heavy steel to light aluminum rims should decrease rotational mass and translate into an easier pull.

I would think that most of these things should result in a slight increase in milage, but is an increase of 1 or 2 mpg worth the $600-$700 your going to spend?

Gary

[brian_bp]

I suspect that the tires from those cars would be so much bigger than a ideal for typical teardrop that there might be no net benefit. Even the light (rear) end of something like a Prius has an axle capacity of 750 kg (almost 1700 lb) or more, so the tires are quite a bit larger than most teardrops use. With a big enough teardrop, or a small enough tire of this type, I think it would help.

[angib]

What I would be curious about what would be the result of using low resistance tires found on hybred cars from Toyota or Honda.

I doubt the rolling resistance of wheels/tyres is as great as their aerodynamic drag - the biggest saving would be achieved by using the smallest tyre that can carry the load. So for low drag, go for 12" or 8" wheels.

I don't think bearing grease choice offers an opportunity to save much - more important would be not to overfill the bearing, as that will cause 'churning' losses - but they're still miniscule.

Reducing wheel weight won't reduce trailer drag any more than saving the same amount of weight anywhere on the trailer - any weight saving you do will improve fuel mileage, but not by a lot - you probably need to trim something like a quarter of the weight off a trailer to see a measurable difference.

Andrew

[mikeschn]

Hopefully the better resourced members here can gradually conduct these sort of tests and offer up a handy-dandy comparison chart with the different tear profiles. Mike? Sounds like your call to glory, you CAD-luvin' tear beast, you!

Who me?

I agree with Doug and Andrew that the wheel size is in the eye of the beholder. Maybe some day I'll take a design that I have a solid model for, and try the various sized wheels.

Here's an example I did a while back...



Mike...

[TinKicker]

If anybody's really interested in mpg increases, check out http://www.hypermiling.com/. Some of the tales they tell are pretty wild, and I'd really have to see it to believe it, but they also give some solid fuel saving advice.
I went from 18mpg in my '04 Tacoma 3.4 liter up to 23mpg by putting out maybe a 75% effort based on their info. Of course, in "real life" I don't get that because I'm always towing or in stop and go traffic or something. The 23mpg was under ideal conditions which will probably never happen again. HA! Day to day I maintain about 20mpg. PM me if you're interested in what I've done.
The cut-to-the-chase rule of thumb is that for every 300lb you drop from vehicle weight you gain 1mpg. Clean out those trunks! You'd be surprised what it'll add up to...
Happy camping.

P.S. - Mike, love the wheel/tire setup! All you need are some of those spinning hubcaps for some major blingage!!!!