Bigger tires/more weight?

[woodys3b 0]

Just moved up from a B-80 to a 1980 C-121 for mowing my 4 acres which has some very steep hills. The C-121 goes up the hills just fine but when going down, it will lose traction and take off, skidding one wheel. It has after market tires on it and I'm not sure they are the correct size. I want to buy some tires with a more aggressive tread but I'm not sure how big I can go. I would like to get as much tire on the ground as possible so bigger is better.

What is the size of the tires that came on it? How much taller/wider can I go on the original wheels? Can I add weight to the rear of the tractor? If so, how?

Thanks

[C-Series14 15]

First of all, your C-121 is a 78-79 model. Original size was 23x8.50-12. I have several tractors with 10.5 AG tires and 8.5 AG tires. You can get wheel weights. You could also build a rear weight rack. Look at my photos in the gallery for pics of tires and WH wheel weights.

[woodys3b 0]

Thanks.

Any chance of getting a 24 inch tire on there without getting too close to the fender?

Also, do you know of a sourse for wheel weights?

[C-Series14 15]

I have seen 24's on tractors. As far as wheel weights, EBay, dealer, on here, othe many other Wheel Horse discussion and classified sites, etc...

Do a Google search for garden tractor wheel weights and have fun!! There are alot of styles out there!

[gwgdog66 23]

I would shift to low range (assuming this is an 8 Speed) before going down the hills. Let the tranny and engine do the braking :thumbs:

[linen beige 14]

If you are loosing traction then going to a larger tire will amplify the problem. A larger tire will put more surface area on the ground and spread the weight out, reducing the friction of each square inch of tire against the ground. To increase traction you need to increase the friction of each square inch of tire against the ground. The easiest way to do this is to go to a more NARROW tire. The second easiest way is to add weight.

You MIGHT (slightly) increase the stability of the tractor on side slopes by going to a wider tire, but you would still need to add weight to maintain the traction. Since you are operating on a hilly yard you want your added weight on your wheels (or inside the tires by loading them) rather than hanging off the back, side or front. Wheel weights are available from a multitude of sources or you can make your own pretty easily.

If you are going to change tires, you may want to go with an ag/lug tread. Some folks claim they tear up turf too much, which might be true in some cases, but if your turfs regularly spin and/or scoot they are undoubtedly leaving marks in your grass. The ags will be less apt to do that.

[woodys3b 0]

gwgdog,

My tractor is an automatic so I can't shift to low. I do go very slow though so I follow your thought process. When I mow the same area with my old B-80 4 speed, I used 1st gear up and down the hills. Dragging a little break seemed to help a bit.

Linen,

I follow your thought process as well. I'll stick with the original tire size. I think Ag tires may be too much but I can certainly get something more aggressive than what I have. I guess I'm in the market for wheel weights. I see lots of what appear to be plastic containers that you fill with sand or cement. These don't look very good to me. I would rather get some cast iron weights. Correct me if I'm wrong on this. I would also consider adding liquid to the tires but don't want to make it ride too rough. Any recommendation to the ratio of air to liquid for a good compromise?

[GlenPettit 1,717]

(1) If the turf tire* is slipping (spinning), then you need traction = more low weight. Lug tires or chains would help, but it's more weight (per sq inch) that's best.

(2) If the tractor speed just slows down and can't make it up the hill, then suspect the condition of the drive belt; if it's the original belt it has likely stretched and should be replaced with a TORO/WH belt. "Belt dressing" will help a revive a belt that has become slick/hard and slips in the pulley.

(3) Liquid will not change the ride in 1st or 2nd gear, but avoid using 3rd gear with bumps, the ride is smooth with liquid when mowing. The rato is 80%; a 8.5x23" tire can have 5 gal of liquid and about 1.2 gal of air (at about 10# psi), just remember valve up when adding air. 'Rimguard' is best (google it), but avoid Salt Brine. For weight, figure: RV & Antifreeze = 8+#/gal, Rimguard = 11#/gal.

If you're also using this tractor in the Winter, also consider some more weight in the front tires to help steering, front weight would help stability some on hills when mowing.

*assuming you do have reasonable tread left on the tire.

[gwgdog66 23]

gwgdog,

My tractor is an automatic so I can't shift to low. I do go very slow though so I follow your thought process. When I mow the same area with my old B-80 4 speed, I used 1st gear up and down the hills. Dragging a little break seemed to help a bit.

Linen,

I follow your thought process as well. I'll stick with the original tire size. I think Ag tires may be too much but I can certainly get something more aggressive than what I have. I guess I'm in the market for wheel weights. I see lots of what appear to be plastic containers that you fill with sand or cement. These don't look very good to me. I would rather get some cast iron weights. Correct me if I'm wrong on this. I would also consider adding liquid to the tires but don't want to make it ride too rough. Any recommendation to the ratio of air to liquid for a good compromise?

I'm tracking with ya now Woody.

[woodys3b 0]

So I read somewhere here or saw pictures of a tractor like mine with 10.5 inch wide tires on 8.5 inch wide rims. That prompted me to buy some of these in 23x10.5x12. They look much wider than the tires that are on there now. So much so that I'm a little worried that they may not go onto those rims. So, before I take them down to the tire shop to mount, can someone reassure me that they will indeed fit?

Thanks

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[buckeye 5]

They will fit. They wont look as wide when they are mounted and aired up.

[GlenPettit 1,717]

You can mount the 10.5" wide on a 8.5" wide rim, it will work fine.

Your wider tire will be a little 'rounded' so less of the tread "footprint" will be on the ground, as compared to a wider Rim; maybe 90%. Also, if you are driving fast in 3rd gear and make a sharp turn, there is a greater chance the wider rubber tire could pop off the smaller rim, slightly greater (also, fast driving over rocks or rough areas might pop this tire), but with normal driving, nothing to worry about. Lower air pressure is better on mowing turf, 10#, and the tires will be wider, if at 20# you'll a smaller footprint but tighter seal.

Go for it, you'll be happy. Also nice looking tires. Check for clearance to the fender.

Glen

[woodys3b 0]

Cool. Thanks guys, I feel better now.

Will be picking up wheel weights from Kelly at the show on Saturday but won't have the time to get everything mounted up for a couple of weeks. I'll post some pictures and impressions when I do. I was planning to go with weights and beet juice in the tires but I'm having second thoughts. Maybe these tires and weights will be enough.

[Curmudgeon 28]

I'll disagree with the bigger tires will make the slipping worse. My proof? Go to any motor event. Be it drag racing, tractor pulling, 4x4 pickup off road racing, 4x4 pickup pulling, you name it, almost without exception they'll all be running the maximum size tires allowed in class.

Theory may sound good, but in this case, reality is bigger is better.

My personal opinion is, ags. I like ags. Tread design is a bigger influence on a garden tractor than size. Additional weight added via wheel weights adds traction, stability, etc. while adding very little to bearing load.

Lot of people like fluid in tires. My personal experience is, yuck. Sooner or later, you're gonna fill your tire pressure gauge with that stuff. Sooner or later, you'll get a puncture, then you'll have that stuff to deal with while repairing. With the greatly reduced air volume within the tire, it will be a rougher ride. You may not notice it on a smooth lawn, but mine is kinda rough and I rely on tire flex to save the jolts from getting to my back. It's the only "suspension" you have.

[woodys3b 0]

Thirdroc is correct for the most part. So is Linen beige. I didn't want to get into a physics lesson here but the math is fairly simple.

The amount of force required to make something like a tire slide is dependent on the amount of friction between the two surfaces. The friction is dependent on the coefficient of friction which is the relationship between the tire and the surface in this case tread and type of soil, and the force pushing the two surfaces together, in this case weight or pounds per sq in. Increasing weight always increases the friction. Adding area (bigger tires) always increases friction but it decreases pounds per sq in. The variable here is the soil. The soil can only take so much force before it looses traction on itself and shears beneath where the tire and the soil are interacting. If it is soft and sandy like mine, bigger tires help spread the load. If it is very hard, you can get by with narrow tires. Around here, the farmers plow in the spring with big 8 wheel drive articulating tractors. Lots of surface area to keep from sinking in the wet soil. If they had just added a ton of weight to a two wheel drive tractor, they couldn't even drive across the field with no plow attached. On the flip side, it the surface is very hard and slippery, the best solution is minimal surface area and max weight. People who live in the snow belt understand this very well.

Anyway, I have mounted the tires pictured above and added wheel weights. No liquid in the tires. On the slopes that I was previously loosing traction on when going down hill, I can now stop the tractor and back up it in reverse. I added surface area and I added weight. Both of these things made a huge improvement! I also have a pretty rough surface to mow. I can run about 10-12 psi in these tires and the ride is much smoother than before.

[tgranthamfd 29]

Glad to hear that the traction was the culprit instead of the hydro. Now where is the eye candy? :)

[wh79d160 52]

I second that !! That sounds like it would look pretty killer. :)

[woodys3b 0]

I still have some Hydro issues to sort out.

Will go take a couple of pics tomorrow. They do look sexy!

[tgranthamfd 29]

Did I miss it or did you say how much those nice looking tires cost you? What are your hydro issues? These guys really know their stuff.

[woodys3b 0]

Pic 1

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[woodys3b 0]

Pic 2

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[woodys3b 0]

Found a before picture with the 8.5 inch tires.

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[woodys3b 0]

Did I miss it or did you say how much those nice looking tires cost you? What are your hydro issues? These guys really know their stuff.

Cost was about $100 each mounted. I was kind of shocked at the price till I picked one up. They are 4 ply and seem to weigh about twice as much as the ones that came off. The luggs are very deep. I went with 23 inch tall tires because I was worried about clearance under the fender. Turns out that the clearance issue is between the tire and the back of the mower deck when the deck is in the up position. The 23 inch tires clear fine but 24 would have been a little too close for comfort.

Hydro issues were discussed in the transmission section and I got a lot of good advice at the Michigan show. Haven't had a chance to "tune it up" yet but will be changing the oil/filter and pulling out a few valves to check their condition. It works but is kind of jerky and doesn't maintain speed on hills very well.

One last observation on the tires and weights. We had some rain here a couple of days ago and the moles went crazy in my yard. I set my traps and got a couple of the little bastards (pardon my french.) Then, instead of my usual routine of stomping down the mounds and tunnels, I got on my tractor and took care of them with that. The wider tires and more weight made short work out of it. Not as good as a tow behind roller but a lot more enjoyable than stomping. :)

[tgranthamfd 29]

God I hate those moles, they won't even try to run around the backyard if the pointer are out playing around, That is the only way I have been able to catch them. Got 3 German Shorthair Pointers that love to play keep away with moles and squirrels, Sorry S.O.I. Like the looks of the tires on your tractor. :)

[dgoyette 12]

Great tires...I would like a set of those for sure.