R4s on YM169D

Johndeere3720 · Mar 26, 2011

I have had a problem where my R1 tires have been damaging areas where the ground is soft or on well watered lawns (hard not to find in the pacific NW). So i have had the thought of getting R4 tires in the back of my mind for quite some time since the price was to high to justify the purchase. Yesterday I got to look at 2 used R4 skid steer tires with about 50% tread on them. It is just the tires, i would have to purchase some rims, and he wants $30 for them. One concern I had right off the bat was if they were the right size (29") and if I could find rims for them that will fit my tractor. So today I measured the tires i have on my tractor now, what do ya know, they are about 29.5". I don't want my tires to be working against each other when i use 4wd so will 1/2" effect my tractor very much? Do these tires seem like a fair deal? Can I find rims? I know of a few places that may have the right rims, but I would have to ask around. My main goal is to keep the price as low as possible, don't have much $$$ to work with at this time. I am pretty sure these skidsteer tires need 16" rims, will have to double check.

winston1 · Mar 26, 2011

The key to front to rear ratio is the rolling diameter of the tires. You really need to know that and your front to rear ratio to be able to answer your question.

284 International · Mar 26, 2011

Does your 169D have the 8-16 R1 tires on it? According to Firestone's website, they have a diameter of 31.1 inches, and a rolling circumference of 93 inches. I don't know how they figure out rolling circumference, it obviously takes into account variables unknown to me, maybe like sidewall deflection and some amount of tread digging into the ground, reducing the effective diameter? I don't know. Setting pi as 3.1416 gives you a circumference of 97.7 inches.

That's really close to tires with a range of dimensions, like 31x10.50 or 31.50x9.50, or 245/75R16. The only skidsteer tires I've seen fit on 16.5 inch rims, like on 8 lug heavy duty pickup wheels. I would suggest raiding the junkyard or a local tire shop for a set of take-off tires in that size range. 30 bucks is a great price for those tires though, it would be nice to be able to use them. Unfortunately, I don't know of anything cheaply available that has a 6 lug 16.5 inch rim. Make sure you let us know what you discover.

Are you chewing up the ground driving across it, or when pulling implements? As Winston said, make sure to keep track of the ratio between front and rears, too.

Roonabeck · Mar 27, 2011

284 International said:
I don't know how they figure out rolling circumference, it obviously takes into account variables unknown to me, maybe like sidewall deflection and some amount of tread digging into the ground, reducing the effective diameter? I don't know. Setting pi as 3.1416 gives you a circumference of 97.7 inches.

31.1 diameter is 15.6 radius (distance from axle center to outer edge of tire)

If you take the "rolling circumference" 93/(pi*2) = 14.8 gives you the "loaded" radius (distance from axle center to ground surface when tire is carrying weight)

So they're basically telling you the tire gets "squished" by about 0.8 inches when it has some reasonable weight on it. The easiest way to figure out the rolling circumference of a tire is to make a chalk mark on it and the ground where they meet, then drive exactly one revolution (so the chalk mark hits the ground again), and use a tape measure to see how far between the two ground contact points.

284 International · Mar 27, 2011

Roonabeck, I'm not disagreeing with you as far as the math goes, and I understand that the tire will deflect somewhat. But I don't think my tires of that size deflect over 3/4 of an inch (which is what .8 inches will be) under the normal load of the tractor. I haven't measured. What I was thinking is that when driving in soft dirt, the lugs will bite into the soft soil, penetrating deeply for added traction, but also reducing the effective diameter of the tire. I don't know.

I've used the marking of the tire to calibrate my dirt bike's speedometer. I actually used a drop of water, so it left a mark on the concrete slab, then I measured between the marks. (Accurately, I did 3 revolutions, then divided it by 3. This reduces measuring errors.) If you measured a tractor tire the same way, on concrete, it would be rolling on the lugs. If it were in soft soil, it would be on the carcass of the tire, so you get less distance out of each rotation, and the soil will get disrupted by the lugs as they bite, then are pulled out.

Roonabeck · Mar 27, 2011

As far as I know, rolling circumference is supposed to be measured on a hard surface. That's where you'll have the most issues with a 4wd. And I've only ever seen one number given by a manufacturer for a tire, so perhaps it is somewhat an average over the treadwear life of the tire?

I thought I saw both a loaded radius and rolling circumference listed for a tire on firestoneag.com, where multiplying the radius listed by 2*pi gave the rolling circumference listed. However I selected a random tire there and the numbers do not match like I said they would.

Johndeere3720 · Mar 27, 2011

Looks like more information will be needed. For the ratio, is it something like dividing the front and rear tire sizes? These skidsteer tires I would just need when Im working near or on lawns or ground where i need a imprint with less of an impact. Thanks guys for the help!

:thumbsup:

284 International · Mar 27, 2011

Johndeere3720: The ratio is exactly as you described, a comparison between the front and the back. The front and rear axle gear ratios will be constant. Divide the diameter, or circumference, of the front tire to the back, or back tire to the front (it won't matter) of the tires it originally came with, then do the same with whatever you're replacing. As long as it's in the same sequence it won't matter, you're just interested in the comparison between front to rear.

There may be a couple percentage points difference, but that's going to be acceptable. Anytime you turn the ratios get very complicated, very quickly, since the distance each tire travels is different. (As an aside, this is one difficulty with very wide tires in high performance sports cars: The fat tires are different enough in width that the inside of the tire travels markedly different distances than the outside, so in a sharp turn part of the tire is slipping.)

I wouldn't worry that much about it if you can get something close in proportion. I *think* the numbers I've seen are around 3 to 5 percent. Check on what diameter rim the skid steer tires require, but it sure seems like they're all 16.5 inch rim sizes. That's why I was suggesting junkyard takeoffs of pickup/SUV tires. Basically a poor man's version of what Hoye's does for these things. I'm going to go measure what I've got right now, but I think that if you got some steel Chevy 4x4, Toyota, Nissan pickup, or Dodge Dakota tires and rims you could fit them onto your machine, maybe with only a little bit of reaming out the holes. I'm going to measure a set I've got right now for you.

284 International · Mar 27, 2011

Just by eyeballing it, my YM1401D has a 6 lug bolt pattern on 4.5 inch circle. That's the same as the Dodge Dakotas. Some of those pickups came with 16 inch wheels from the factory. (The SUV, a Durango, will be similar.) If you're able, I'd measure your clearances to the fender, footrest, whatever is the nearest set of things that will hit with a different depth or backspacing of wheel.

Then, lay a yardstick or board or whatever across the tire as it's off and laying flat, and measure to the hub mounting surface. You'll get, say, 4 inches or whatever. See if you can move your hub in or out on the axle, too, to gain more room. Now you have a set of numbers to use in your search. Go find a Dakota/Durango (The little Mitsubishi pickups whose name eludes me are the same, too) in the junkyard. Do the same trick there. Then you'll know if they will fit or not. If they will clear ok, you should be able to get a set of rims and functional tires for $100 or so. If you're just using it for mowing the reduced traction won't matter compared to your R1s.

The YM240 is 6 on 5.5, which matches up to Chevy/Toyota etc 4x4 rims. Again, eyeballed. It would be close enough to match with a little drilling, if any.