I like grass strips, but I found that some were marginal with wheel pants, so first I went pant-less. I then tried some rougher strips, which turned out to be marginal with the stock 5” wheels, so decided to take the plunge and install bigger wheels and tires. After completing that project, my interest morphed into flying into backcountry airstrips. The real issue with a backcountry airstrips is that it tends to be farther away from roads – or even inaccessible by road/land vehicle (that’s what backcountry means, right?).

Stepping back a bit, the wheels I installed mandate using inner tubes. You can find wheels that take tubeless tires and fit a 1.25" axle, of course, but the RV-7 is too heavy for Matco’s 6 or 8” tubeless wheels.

More pictures

So what’s the problem? Well, the reason you want tubeless tires in the backcountry is that if you get a flat, you can install a patch, pump the tire up to 4 or 5 psi, and get back to civilization. With an inner tube tire, it’s an entirely different problem. To get to it, you have to jack up the wheel, remove it, split it – yeah, you get the idea... The question is, how to jack up one wheel of the RV-7 while it’s on the tailwheel, preferably without having to carry a ton of equipment, and without risking damaging the plane if it slips off the jack? Unfortunately, the wonderful CMW E-lift I installed on the 5” wheels doesn’t work with my brake flanges (Flyboysaccessories’ RV Jack Points won’t either) and anyway, another problem is that the 8.5 x 6 tire is much wider than the 5.00 x 5, especially when it’s flat so neither of these devices has the required reach!

After much trial and error, I determined that a 10” long 7/8” steel rod with 4” at one end lathed down to 0.865”, coupled with an ordinary automotive scissor jack allows you to lift up a main if you chock the other tire and the tailwheel. After disconnecting the disk from the hub, you can slip the wheel onto the rod and get a jack stand under the brake flange, at which time you can get the scissor jack out of the way, take the wheel off, and take care of business (see pics). You also need to carry the tools required to disassemble everything, as well as an inflator that can get the new tube back up to the required 35 psi. Forget using CO2 cartridges or a hand pump; a foot pump might break down (or you might) before you can get all the air that’s required into the tire, so a 12V car inflator is your only practical option. BTW, I’ve been able to come to a full stop in 750 feet on a smooth strip. It’s no Super Cub, but at least I can get the plane on the ground in a relatively short distance.

Off you go then! The materials list follows. Email me if you have any questions.

Materials

  • Matco

    • 2 x WHLF600 - WHEEL & BRAKE ASSEMBLY 6'' 1.25

    • 2 x WHLAN1H - AXLE NUT, CASTELLATED HEX with BEARING RING, 1.25-16

    • 2 x TIRTU600X6/90 - TUBE; 600X6 TR87 90 Deg Stem

    • 1 x CNVB5-D - CONVERSION KIT B5#-> B5D (D5 DISK) (dual-caliper kit)

  • Aircraft Spruce

    • 2 x AERO CLASSIC SMOOTH TUNDRA FAA TSO TIRE 850-6 4 PLY (PN 06-02501)

    • 2 x STAINLESS STEEL FITTING AN816-4J (PN AN816-4J)

    • 4 x AN4-6A bolts, nuts, washers

  • Local machine shop​

    • 2 x brake flanges. Because the width of the 6" wheel and design of the brake plate is different from the stock 5" items, it was necessary to make special brake flanges. If you have a lathe, you may be able to make these yourself but I gave this drawing to my local machine shop (Profile Machine Works, Manassas, VA) and they made them for me.​ My drawing is rudimentary but the dimensions are correct. Profile may have kept the CAD file, but you'd have to ask them. The photo page has pics of the flange.

  • Replacement parts​

    • ​Matco: WHLBRL-1 Brake reline kit; brake pad (“lining, 5/6” brake” is WHLM66-106)