The International Cessna^® 170 Association

Fellow birdmen/women

I am considering replacing my existing 7.00 tires with 8.5 x 6 units.

If I were to do this, has anybody noticed any significant change in the ground handling characterists of the plane?

I have single puck Clevelands on my 170B, and although they aren't overwhelming, they've got the job done in some demanding conditions. I am concerned that with the larger tires, the brakes might not be adequate if I have to do some serious stomping and screeching.

How does the larger footprint on the pavement come into play, along with the more flexible sidewalls?

Wouldn't there be a slight change in the angle of attack also with the larger units? I do have a Horton kit on my bird, which in my opinion, definitely changed the way it lands/takes off (typically in a good way).

Anyway, experience is everything, so your thoughts will be greatly appreciated.

Thank you.

Just do it. The advantages off-pavement are worth it, you won't notice enough differences on-pavement to write home about.

Joe

How you going to get it approve?

What Tim is saying is that up to 8:00 tires are approved by the TCDS. Over that will need an approval which may be difficult to obtain these days.

I'm running 8:00 with single puck Clevelands and I can lock up the wheels if I try hard enough. 8:00 are slightly larger in height and footprint than the 7:00 your are running and only require a log entry for installation.

8.5s are larger yet but have the hassle of a field approval that goes with them. Only you can decide if the hassle is worth it. And it only stands to reason that your brake won't be as effective with the larger tire.

Another consideration is that some people have had to use spacers so their tires clear their brake pucks. You may have to do this with either 8:00 or 8.5s

Also consider that the brake caliper assy will rub on some tires of that size (8.50) you may have to shim or make up some spacers. Being you are going to go thru the trouble of a field approval, try to find a wheel brake combo that will fit that tire. Hey what does the L19 have?

I have 800's and single puck clevelands. Anything larger and I would have needed spacers. I did notice some loss of braking but managable. I occasionally land off airport. If I was just landing on cut grass, asphalt or smooth gravel runways I would go back to 600's
Better braking, a couple more mph, cost, slightly less grabbing when landing on asphalt in cross winds. My opinion only.
Bob

I did it to my 54B and love it. I have single Clevelands and have had no problems... Got it approved with FAA no problem either... The only hang up was the tubes were on backorder.. it took and extra 2-3 weeks to get tubes.. this was back in Sept 2006 so tubes may not be factor now....

Jim
2521C

For what it's worth, my experience with 8.50 tires:

1. My single puck brakes were marginal. I changed to double pucks.

2. Brake clearance was adequate, whereas I had to use spacers with 8.00s. It may depend on the tire brand.

3. Any wheel misallignment seemed to be amplified with the larger tires.
I realligned mine to clear up rather squirrely ground handling on roll out.

4. I reverted back to 7.00s since I was more concerned with rough ground on turf runways, and price, rather than footprint area.

5. I never bothered to ask for installation permission figuring that begging for forgiveness was easier. and more likely to be successful.

mrpibb wrote: Hey what does the L19 have?

7:00-6. I struggle to understand why anyone needs bigger, absent flying onto a sand or gravel bar.

Why would anyone own a tail dragger if they weren't flying into sand or gravel bars?

AR Dave wrote:Why would anyone own a tail dragger if they weren't flying into sand or gravel bars?

Why would you own any Plane you couldn't go off the asphalt with

AR Dave wrote:Why would anyone own a tail dragger if they weren't flying into sand or gravel bars?

Amen! Nice looking bird, Dave.

I put 8.00's on mine, since it was time for new tires anyway and I replaced my Goodyear X-wind gear with a Cleveland kit. I did notice the clearance between caliper and tire is only about 5-6mm. That doesn't seem enough but I was assured it is. I had a bad dream about being a little low on tire pressure, landing hard and the caliper opening my tire like a can opener.

I used to have 8.50x6 tires on mine and brake clearance was no problem. The single pucks are minimal for them but still safe. Blueldr is right though make sure that gear is aligned good. I have double pucks now with 31" Bushwheels.
Shawn

Just switched from 7.00's to 8.50's (Goodyears.)

Using them to fly in and out of a strip that has too much snow for smaller tires but not enough (really) for skis. But I'll probably keep them on since most of my trips are pretty short and the extra drag really isn't important to me.

Here's a photo of it tied down with the 8.50's.



Supposedly the Goodyears tend to be a little "fatter" and not quite as tall as some of the other manufacturer's 8.50x6.

Fortunately my plane already had the field approval done some time ago Though if it didn't already I might have gone with the 26 inchers instead

My initial opinion is that I don't notice a whole heck of a difference in ground handling, actually.

Does your 170B have at least the lady legs? A couple folks have said look out for in-flight vibration with 8.50's and weaker spring gear but maybe that is an OWT. I have the lady legs and even in the yellow arc there is minimal vibration noted on the pilot's side.

Brakes are somewhat of an issue. The single pucks are safe but marginal. I did note the difference in braking with the new tires. I will be getting double puck brakes and C180 gear legs sometime this year after the bank account builds back up some.

What is the diameter of these tires?

My Air Trac 7.00s are about 18" in diameter. Inflated and off the ground.

What are 8.00s, 8.50s and 26" Good years?

How much cruise speed is lost when switching from 7s to 8.5s?

Bill