The International Cessna^® 170 Association

When I first started looking at the 170 that I would eventually buy the owner had Goodyear 26x10.5-6 tires on the plane (Very appealing to me, just love the look). All of this looking was via pictures as it was about 28 hours away. When I made a decision to make the trip in hopes of buying the plane I did not have a tail wheel endorsement so the plan was if I like it I’ll buy and get trained in it at the remote location and fly it home. So the owner felt like I would be better off having the 6.00-6 tires on for the training sessions and then move up to the bigger tires if I wanted to at a later date. I agreed and the smaller tires were on when I arrived. Sorry for the long story but trying to give some background for ya. So I had never physically seen the big tires on the plane. I had the tires shipped back home and a couple weeks ago I felt like I was ready for the bigger tires.

So the bigger tires were put on last night but as I tried to put the back brake plate in place I noticed there’s not much room here. Looking at it in more detail (The light was fading fast on me) I could see where there was a groove warn into the tire from rubbing against the brake caliper. Same for the other tire after taking a look at it before mounting it on the wheel. After some reading on the forum I saw some discussion about spacers that could be used to put some room between the caliper and the tire. Is this an option for me and where might I found such an item? Also saw some discussion about the bigger tires causing gear box failure because they are two big for the gear. Does this concern apply to these size tires?

To add to my concern after doing a bit more research I found out via the Goodyear site these tires are not STC’ed for use on a 170. So a field approval would be needed. I was unlearned in this area so this was never discussed with the previous owner. I am guessing there should be some entry in the log book showing this field approval if one was obtained, if not where should I found this if it exists.

If it does not exist, what issues might this cause for me?
Thanks for your time,
Justin

Sorry gang for the double post. Not sure how I did it but obviously I did. I don't think I can get rid of the dup on my own so maybe Mr. Horn and Mr. Fenstermacher will assist me with correcting my error.

Early on, when big tires were being mounted on Cleveland wheels there were 1/4 inch spacers (after market) available that went between the wheel and the brake disc.(Single and double puck brakes) This eliminated the rub issue. Longer wheel thru bolts where required. STC and Field approvals were used. I think Reeve Airmotive of Anchorage still sells them. 907-272-8522 ask for Dan Nation.

juredd1 wrote:Sorry gang for the double post. Not sure how I did it but obviously I did. I don't think I can get rid of the dup on my own so maybe Mr. Horn and Mr. Fenstermacher will assist me with correcting my error.

I think George has the site set up so that double posts only happen when you've been drinking, which explains at least a portion of his post count...

Been known to happen....(it's spel'd--- drankin')

I would presume that a couple of washers beneath the brake disc, between the disc and the wheel, might cure this problem as long as the thru-bolts were long enough. It doesn't look like much clearance is needed.

Actually tire offsets are used. I have a pair I'm not using. $35/ plus shipping if you want them. Doug

Are the spacers needed for 8.50s or just the really big tires?

It depends, some of the 8'50 tire manufacturers changed the sidewall design and now don't need spacers. I can't remember who.

It depends, some of the 8'50 tire manufacturers changed the sidewall design and now don't need spacers. I can't remember who.

I just went through the process of getting the required approval for goodyear 26" tires on my 170B. was not that bad. the FAA guy here in Mt. was great. The only thing I do not like about said tire, is they seem to skid more easily on wet grass, and shallow snow. If you need any of the paper work that I used, get a hold of me, I would gladly help. Francis Cahoon

Thank ya for the replies and much needed info. Any concerns about the tire size/gear leg combination? Also any advice about what I can expect on take off and landing compared to the 6.00-6 tires.

One other thought, the current bolts just barely extend past the head of the nut currently so I would expect that I might need longer bolts. Is there something specific I need to look for and would expect to be able to get those from aircraft spruce or some other aircraft supply store?

Doug,

I'll PM ya about the tire offsets. Thanks.

Francis,

If I can't find the 337 or anything related to the approval of these tires I will give you a shout.


Justin

juredd1 wrote:...I might need longer bolts. Is there something specific I need to look for and would expect to be able to get those from aircraft spruce or some other aircraft supply store?
...
Justin

Aircraft bolts are described by diameter (AN5 are 5/16" diameter) and length ("dash" numbers) which describe the length.

Here's a chart which will help you understand: http://www.aircraft-spruce.com/catalog/hapages/an6.php

You will find them at Spruce, GEM, GenAv Hardware, etc etc.

Thanks George for the information.

Francis,

What air pressure do you run in your 26's? I was told between 15 and 30 psi. I'm guessing off pavement being on the lower end of that would be the best.



Justin

Justine, the tire pressure that I have been using is 12 lbs. I have landed on grassy flats, along the river, on grassy semi rocky hill tops, semi sandy soil, and only pavement when I need fuel. this pressure seems about right for what I do so far. Pavement, the tires seem a little sticky, and in my meager experience, this might be the most likely time the tube might spin on the rim, therefore I check the mark I put on the rims and tires each time I fly. I first tryed 10 lbs, but seemed really unstable with side to side movement. That is just my opinion. I do like the tires better than the 800s that were on the plane.

canav8 wrote:Actually tire offsets are used. I have a pair I'm not using. $35/ plus shipping if you want them. Doug

What is a tire offset?