Folks - anyone running 31” ABWs on a 170B?

I’ve got 26” on now, probably am not doing anything that needs 31, but, well, they look cool.

I’m already slow with the 26 and the 80/42 prop. Any direct experience with how much more speed I’ll scrub off?

Sure, they look cool, but 26" is still a sizable tire. And for $3600 I'm sure there are other things you could do to the airplane that make more sense.

Do you have a sportsman? Double pucks? 180 gear? Beef up kit?

What about flashing LED light so people can see you?

After that I'd look at a fuel computer or a garmin G5.

schu

It’d be damn nice if I just said “yes” to that list above.

What does that sportsman really get you? I get 40 mph indicated in a powered approach to the deck and still barely get 3 point. Perhaps I do not have correct indications.

Jergens786 wrote:It’d be damn nice if I just said “yes” to that list above.

What does that sportsman really get you? I get 40 mph indicated in a powered approach to the deck and still barely get 3 point. Perhaps I do not have correct indications.

Probably correct...my 170B airpseed indicator goes to zero when my GPS says I'm still doing 60mph. It's the angle of attack of the pitot tube at that speed...not an accurate indication.

I have no idea if those tires are a good idea or not, but if you're curious...and have the money...and want to look cool...go for it!

If you don't like them they're probably pretty easy to sell.

I had a 170 with 26” bushwheels, 8042 prop, and sportsman STOL kit among other mods. I would HIGHLY recommend the sportsman STOL kit before going to 31s. It was probably the best thing I did for that airplane. You’ll get in and put shorter while having more control at slower speeds and 26s are already plenty of tire for a 170. 31s would be fun too but I’d go the sportsman route first. Also if you have the early gear legs like I did I wouldn’t go any bigger on the tires without 180 legs, or at least lady legs. The early gear is pretty soft for any more weight than 26s.

After eight years of running 8.50 tires, I switched to 29 Bushwheels on my O-300 powered 170 with a sportsman STOL kit. The bigger tires are incredible during landings. The spool up drag from getting the extra mass spinning with the bigger tires was definitely noticeable on takeoff. Even more so when running lower pressure. As we all know, a 170 with stock powerplant will typically land a lot shorter than it takes off with any significant load on board. Something to think about... 26" bushwheels might be the sweet spot.

Jergens786 wrote:It’d be damn nice if I just said “yes” to that list above.

What does that sportsman really get you? I get 40 mph indicated in a powered approach to the deck and still barely get 3 point. Perhaps I do not have correct indications.

No, your airspeed indicator isn't correct at those angles.

Also, what do you mean by barely get a three point? Are you saying the airplane stalls just before you reach 3 point attitude, meaning you can't get the tail to touch at the same time?

If that's the case then absolutely sportsman, it adds a bit of wing area and I believe you get a higher AOA before stall.

My 170A has a Horton stol kit and VG's on it, and with 26" Goodyears (on 185 gear) I can have the tail a good foot or more closer to the ground than the main gear on landing. I actually have to be careful to not bang tail first.

That means I could benefit from the taller main tires, but I'm not going to buy bushwheels, I'm waiting for the STC for the desser setup with tubeless wheels. I think they will perform almost as well in soft terrain, but a lot cheaper overall, and I'll still be able to land on pavement without wearing stuff out.

schu

A couple of questions:

1. Do you NEED that big a tires? Frankly, if you don't really NEED them and USE them where they're intended to operate, you're wasting your money, by the bucket full......

2. One of the limitations of the 170 is the gross weight. Unless yours is REALLY light, you won't have a lot of useful load. Add those big tires and you eat up more useful load in exchange for tires you may or may not NEED (see 1. above).

3. I've found the 26 inch bushwheels to be a pretty fair all round tire. 31s are pretty serious off airport tires in my opinion. If you're doing a lot of that, go for it.

4. Bushwheels wear relatively fast if used frequently on pavement/concrete. Are you based on grass/gravel, or pavement? Better to wear out $1100 tires than $2000 tires.....

But, hey, it's your money. But, whatever you do, get a Sportsman kit installed.....seriously.

MTV

I heard someone say that the Sportsman STOL costs a little cruise airspeed, any truth to that rumour?

Jergens786 wrote:Folks - anyone running 31” ABWs on a 170B?

I’ve got 26” on now, probably am not doing anything that needs 31, but, well, they look cool.

I’m already slow with the 26 and the 80/42 prop. Any direct experience with how much more speed I’ll scrub off?

Let's examine this. Do 31's look more cool? Check. Do they fly slower? Check. Logical conclusion is you will spend more time looking more cool. You're welcome.

-DP

p.s.

Wow, I had to wade through a lot of opinions unrelated to the original post's only question:

"Any direct experience with how much more speed I’ll scrub off?"

All that hot air and still no one willing to offer an answer to a simple question?

My sense is that if your choosing to install larger wheels speed isn't the issue or even a concern, just saying !!!!!

I found 26s to be all the size increase I ever needed-
Kept me from dropping into rodent holes and reduced rough surface roll out vibration to keep from "Smokin' rivets.

I would put my money towards several other suggestion above
Any one of them will do more good than "looking cool"

MrPants wrote:Wow, I had to wade through a lot of opinions unrelated to the original post's only question:

"Any direct experience with how much more speed I’ll scrub off?"

All that hot air and still no one willing to offer an answer to a simple question?

As if this is on point...

What a worthless community of fliers you have stumbled upon MrPants... Folks willing to offer their directly related experience and advice without offering exactly the answer that the OP was seeking...

How dare we all spout off with all of this "hot air" without giving him the exact speed he will lose...

When I went from 850’s to 31’s I lost between 6-8 mph. Can’t remeber exactly but is was considerable. 26” to 31” obviously not as much difference, but there will be a speed penalty.

I agree with others as to spending money on other performance enhancing mods first, but if you want 31’s, buy them. It’s your money. If you have lots of asphalt ops, they will wear out faster than you want. I know this from experience. Not because a friend told me so.

Switch 26 to 31 on my cub cost me 4-5 mph. Almost an answer to the question.

The Sportsman was the best value for money that I have spent on my 170. The 80X42 the best fun for the money. I run 8.50s but would like to go to 26s. I think if I had the budget for 31s they would only go on for special occasions, the on pavement wear puts me off.

So this is second hand from a friend of mine this week. He put a set of 31's he had laying around on in place of the 8.50
Goodyears on his 56 180 with a pponk. Said he was surprised by the speed loss, I said lost 20 mph? His response was "more like 15 to 145 at 23 squared". He usually flies at 2000 to 2500 msl cruise. All I know, hope it helps.

tim

Awesome! Thanks for the info akgreg, Coyote, and batt443. As someone who is going to put bushwheels on my bird, this insight is very valuable.

I run 29 inch bushwheels on my 55 170. With out a doubt I lost 10mph on a good day 15 is more realistic. Am I unhappy? Absolutely not! I run 31 inch Dessers on my 180 . I can’t wait till grove gets there tubeless wheels approved. I will run 31 inch Dessers with tubeless wheels on both planes. The only time it’s a problem is when you’re flying with friends and you find you are the slowest of your group. As long as you’ve got an airport identifier its okay.