RV7Guy

RV7Guy

Well Known Member
Hi Everyone,

Last annual (okay, Condition Inspection), I replaced the tires from the stock units. (I forgot the brand I put on) No problems, everything good. Fast forward to a couple of weeks ago.

I was flying to work, Chandler AZ to Yuma AZ. As I was about 30 miles out of Yuma, Approach Control announced the airport had just went IFR. The front edge of thunder storm was blowing dust across the field. I had the storm on the 496. Despite reporting the airport IFR, I could see it 20 miles out. Obviously the ground vis was much worse than the air visibility. I pulled out the Approach Charts and was cleared for the 17 VOR approach. No biggie despite being my first "real," IFR approach in the plane.

Did the approach, then asked for a Circle to land for a better wind situation. I had a left quartering head wind at about 25 knots, gusting to 30. Touched down and the plane bounced slightly. The second touch was not straight. Not a huge deal and I taxied in to our facility. (I've had worse!!)

The next day I flew to CA with no problems and returned later. When putting in the tie down rings I noticed cracked paint on the inside of the right wheel pant. Upon inspection, I discovered the tire had grabbed the back of the wheel pant and pulled the glass in and was very close to the glass, even with the minor damage. I checked the other pant and the gap was approximately 3/8," with full tire inflation. I knew the right tire was slightly lower than my normal pressure and was going to add the air while working my 7 days. One of those things that would hardly be noticeable to anyone else, but you know your own plane.

I took the wheel pant off and made minor repairs to get home for the real repairs. I discovered the right tire was down only 2 pounds from the normal 35lbs.

What I discovered was the new tires had a larger diameter. Comparing with the old ones it was at least an additional .5 inches. I took the time to open the holes in both wheel pants.

So, two things to consider. 1) If changing brands of tires, confirm your tire to wheel pant clearance. 2) Always keep your tire pressure accurate. Under normal circumstances, I probably would have been fine. With the slightly low tire pressure and the crosswind touch down, it was enough to deform the tire and grab the pant.
 
Good catch. On a side note, I used to run 35-38 lbs. of air in the tires, but after some experimenting I now run 50 lbs on all 3 tires (7A). I have the Grove nosewheel, and I balanced all 3 using a motorcycle wheel balancer. Everything is now smooth as silk throughout all speeds. I was amazed at how many weights the wheels took to balance them.

Vic
 
vic syracuse said:
Good catch. On a side note, I used to run 35-38 lbs. of air in the tires, but after some experimenting I now run 50 lbs on all 3 tires (7A). I have the Grove nosewheel, and I balanced all 3 using a motorcycle wheel balancer. Everything is now smooth as silk throughout all speeds. I was amazed at how many weights the wheels took to balance them.

Vic
Click to expand...

I'd like to balance the mains on my -4. Can I simply bring the wheels to a motorcycle shop and ask to have them balanced? Where are the weights attached?
 
I balanced all the wheels on my 7a and when I took them to the motorcycle shop they said they couldn't do it. I took them to the airport FBO and was able to get them done, they ended up with a bunch of weight to balance them.
 
Small diameter wheels almost always seem to need more weight than you would suspect.

Moment arm at work here.
 
Mike S said:
Small diameter wheels almost always seem to need more weight than you would suspect.

Moment arm at work here.
Click to expand...
no doubt it will take twice the weight as the actual out of balance condition if it is in the tire.

the out of balance condition is probally not as bad as it appears by the added weight.

are they static balancing or dynamic?
 
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Another thing I've noticed is that our bias-ply tires grow a bit from when they are new-- typically 1/4" per side. It only takes a few landings for them to do that. Don't know how much they grow in diameter, but probably the same as width. The lesson here is don't skimp on tire clearance in the wheel pants when you're building. I had to open mine at least 3/8" all the way around after flying for a few hours.

Heinrich Gerhardt
RV-6, flying
 
Proper clearance?

Hi all,

I am about to fit my wheel pants. What is the correct amount of clearance? I am wondering about the bottom (ie ground to bottom of pants) as well as the side to side and end to wheel. What has been successful? I am conventional gear -8

Regars,

Michael Wynn
RV 8 FWF
San Ramon, CA
 
Any input on the tire/ wheel pants clearance when on the ground? I'm currently at about 1/2 inch but haven't flown with the pants on yet. Is that going to be enough?
 
Clearances -

After experiencing a cut tire during my test phase, I opened the clearance up to about a thumb's width, and that seems to work pretty well. No measurable/repeatable speed change, and more peace of mind.

Paul
 
clearances

While my 14yr old was doing the take-off, he managed to get the plane VERY sideways. So much that the outside wheel was "skittering" or "scuffing" during the heading correction. Later, while pushing the plane into the hanger, I noticed that something was dragging!
Turned out that part of the wheel pant had folded up, and was rubbing against the tire. I had about the width of a thumb clearance to start with, and it just seemed tight to me, but all my RV buddies agreed that this was OK clearance.
The witness marks left by the tire suggested to me that about a thumbs "thickness" (measured at the bottom of the thumb nail, of course) should be added to the original thumb width to get a little more clearance.
Glued the pant back together; cut off about an additional 1/2 to 5/8 and called it good.
Tire pressure measured 23 - 24; I put it back up to 30.
 
My minimum....

.....is 3/4" since I too, have had a student land somewhat sideways and the tire pulled the bottom edge of the wheelpant up, folded 180 degrees.

Regards,
 
So it sounds like the 1/2" isn't going to do. I"ll open that another .25" to 3/4 then.
 
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