Da-40 Rear tire size

[Enrick]

Hi there,

Aircraft came out for annual and i decided to put 2 new rear tire, the tire i have on it right now is the smaller one, goddyear 15X6.00X6

and the original tire is 6.00 X 6.

can someone know the benefit of this... i alway said that the aircraft is hard to pull with tow bar, diamond put complete new bearing, brake, disk pad, ther are due to be done, but i thinking this was the problem, but not. still hard to roll them with the tow bar. and the wheel are completely free,

and i saw other da-40 adn i said they the rear look higher than mine, and why... my bird looks to have the tail low

[krellis]

First, make sure tires are inflated properly. Another possible issue is that the main wheel alignment is off. Dragging brake or bad bearing is also possible, but in my opinion, less likely.

[smoss]

A few things greatly influence how easy my plane is to pull or not. 1-new grease in the bearings. I use the recommended AS Grease 5 in the bearings, and the stuff is thick. Right after annuals always, it's definitely harder to pull. 2-when it's cold out, it's harder to pull (presumably because the thick grease is stiffer). 3-full fuel and some bags in the plane make it significantly harder for me to pull (I weigh 150 lbs), half full fuel and no bag, easy to pull.

[Enrick]

Hi there, Diamond aircraft factory last sumemr made complete landing gear bearing change, front and rear, new disc and brakem brand new grease, summer or winter still hard to pull, but i can tolerate this, im a 260lbs guy, but my cow owner 160 lbs, have problem.... i think i will buy the an electric tow bar...

but for the tire size, the 15x6.00x6 tire are 13 inch hight and its a wide tire, and the original tire are 6.00X6 tire and are 19 inch hight so its 6 inch higher and less wide than the 15x6.00-6

the rear tail skide plate are at 21 inch high from the ground with the 15x6.00-6 tire

so i make my choice this afternoon, i remove this brand new tire adn will put the original 6.00-6 tire

with the 15x6.00-6 tire, you walk back and see the aircraft rear low like a droped car, i saw a lot of da-40 adn they not look like this...

[smoss]

be aware there a several different landing gear struts on different DA40's, the standard, the performance, and the "tall". I think only the 15 x 6.00 x 6 works with the tall and performance due to a different wheel fairing, could be wrong on the reason, forgot.

[Chris B]

Hi Enrick -

IMO, using the right size tires for your gear is the right call!

Separately, you may want to peruse this related thread (link).

FWIW, I run a few PSI higher than spec on the main tires, because:

1. If you read the Goodyear manual, cold PSI is supposedly measured without weight on the tires.
2. Slightly higher is *way* better than slightly low (which IME is a recipe for flats).
3. If you are spotty about actually checking pressure, see #2.
4. Easier to maneuver on the ground. When using the tow bar gets tough,
   it often is a leading indicator that the tires need more air.

Chris

[Enrick]

Hi chris,

but do you know if the 6.00 x 6 is better than the 15x6.00x6 or the other....

[Enrick]

You are right, the 6.00x6 dont enter in the wheel fairing, i do the test today,

[rwtucker]

I follow Chris' advice on pressure. When pressure falls to what is called for in the manual, I fill to about 10% above that.

I think the high towing resistance is a design feature of that tire. My PA28 has similar size tires but with the older high profile. Even though it is is a few hundred pound heavier, the PA28 has half the towing resistance of my DA40. Several times a year, I pull it a couple of blocks between two hangars with one hand behind my back walking forward. Try that in a DA40, at least with my configuration (2007/08 XLS).

This post in Vans was interesting.

(Re: 6.00 x 6 versus 15 x 6.00 x 6) The first group, the 6.00, is section width. Measure the usable tread, even that bit that reaches down the side of the tire, and see the six inches. The second size, the 6" is the wheel's bead seat diameter. The hole in the tire will be smaller so that it jams on the bead seat so braking forces won't spin it on the wheel. There will be tolerances for both of these sides.
A three-part number, like the 15x6.00-6, is giving the tire's actual diameter. In the case given, that is a smaller-diameter tire used on airplanes like our 182RG where the wheels have to slip into rather small wheel wells. And they cost twice as much as a 6.00-6.
A third factor is ply rating. 6.00-6 might be four or six ply rated, while actually having fewer fabric plies than the rating suggests. It comes from a time when the fabric was cotton or linen instead of nylon, which is stronger. More plies means a stronger and stiffer tire for more weight and pressure.

[92838372]

I found the same. My brother's Cherokee was easy to pull. My Diamond not so much. I've never really understood why.