I know I have beat this bush a lot but I'm hoping someone has experience with goodyear mechanical brakes and tires that are bigger than 6.00's. I think these brakes were put on a lot of planes in the late forties.

What I am concerned about is buying a set of tires and then finding out the brakes won't hold as required in the "tundra tire worksheet"...I think is says something about holding when at full power? I'm also concerned about losing braking effectiveness even if they meet the requirements. Anybody used these bakes with bigger tires? Any recommendation on size?

I would like to put on as big of a tire as I can, just for the shock absorption not the cool factor. My IA thinks 8.50 are overkill and perhaps they are but I don't know if 8.00's are enough of an improvement over 6.00's to make it worth the effort.

put on bushwheels and air them down, then you dont need brakes. the bushwheel STC does specify HD brakes though.

Seriously though I think they would handle 8.50s as long as they are in good shape. 8.50s are a big improvement over 8.00s on a cessna 120, so Id imagine bolth would be an improvement over 6.00s. I know a few guys who run them on chiefs with no trouble, chiefs land verry slow though.

I have mechanical brakes on the Champ and it had 8.50's on it at one time. The brakes held but just barely, anything much over mag check RPM would generally overcome braking force. I went to 26" GoodYears and the compound leverage of the bigger tires was noticable. I am now on 26" AKbushwheel Airstreaks and as Currie states....really not much need for a lot of brake with Bushwheels. With low pressure they don't seem to roll as well as a harder tire.
The good side to this is I don't worry about locking up the brakes and going on my nose. I did lock them up on the snow the other day and it was like being on skis. Actually, it ends up that the minimal braking works great for MOST of my landing.
Good luck

I owned a 90 hp J-3 Cub for a number of years, that had the original brakes, and operated in winter on 25 inch Goodyear Airwheels. Braking with that combination was pretty minimal, but that's really not much of a problem with an airplane like this, with such slow landing speeds.

As an old IA told me once, when I was considering buying a PA-12 with original brakes, and commented that I'd prefer Clevelands....."You supposed to FLY the damn thing, NOT stop it..!!!"

From an operational standpoint, I wouldn't be afraid of your brakes with 26 inch Bushwheels, and certainly not with 8.50's..

MTV

Thanks for the thoughts guys. Landing speed is a bit of an issue with a Luscombe. Bushwheels aren't really an option because there is no STC for my plane...paying that much for a tire then having to do a field approval just doesn't make sense to me. I suppose I could adjust the brakes real tight to pass the inspection then loosen them up to where they usually are

Whee, do you have those little round pucks for brakes in your Luscombe? Pedals only on the left side?

Yeah, thats what I got. The pucks are 1.5" in diameter and squeeze the disk that sorta "floats" on the wheel. They work pretty good with 6.00...if I adjust them tight they will lock on gravel but they will be dragging a little all the time. My IA says they aren't worth their weight and I should change them but why fix it if it ain't broke?

I was just thinking about the torque larger tires would put on those brakes. In my Luscombe the brakes were just barely adequate and the only time I used them was when I had to make a really tight turn. One time I got to the end of a really narrow runway with swamp on both sides and discovered that only the left brakes would work. I tried to swing it around but overshot with no brakes to stop the turn. So I tried again and again and again. About that time I noticed a 172 sitting on the taxiway watching me. I always wondered what he made of the little show I was putting on.

Most Luscombe guys tell me similar stories. Mine work better than most I suppose. One time I landed in the Arco desert and when I turned around to take off I didn't want to drag my tail through all the sagebrush so held the brakes, picked up the tail, pivited around the right wheel 180 deg and took off. So the brakes aren't great but if they are maintained properly they will do their job.