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  1. #1
    Veteran Member
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    Cooke County, Texas
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    JD4320 with TNT, electric diverter, cruise control and air suspension seat.

    Default Any disadvantage to using smaller diameter tires

    I will be purchasing a new tractor next year, either a TC55 or TN60/70 or possibly a JD 5320 or 5420. Was wondering what the disadvantages would be to purchasing a new tractor with smaller diameter R1 tires? For instance, instead of getting rear tires of say 16.9-28 or 16.9-30, what about ordering rears of 16.9-24? This would also call for a less wide tire in the front: 8.3-24 vs 9.5-24 or 11.2-24 in front.

    The advantage I see would be a lower center of gravity for the tractor, which I believe would be a plus. Other than a lower overall weight, would there be any other disadvantages?

    Thanks,

    froggy

  2. #2
    Super Member Robert_in_NY's Avatar
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    Silver Creek, NY
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    Case-IH Farmall 45A, Kubota M8540 Narrow, New Holland TN 65, Bobcat 331, Ford 1920, 1952 John Deere M, Allis Chalmers B, Bombardier Traxter XT, Massey Harris 81RC and a John Deere 3300 combine, Cub Cadet GT1554

    Default Re: Any disadvantage to using smaller diameter tires

    Taller tires seem to pull better, one disadvantage of the 24's is that you lose a few inches of clearance. Tires are a customers preference, I get the biggest and widest I can because I need the clearance and flotation. I guess that is the biggest drawback, you might get stuck or hung up a lot easier then I will with the same machine.

  3. #3
    Epic Contributor
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    jinman's Avatar
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    Texas - Wise County - Sunset
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    NHTC45D, NH LB75B, Ford Jubilee

    Default Re: Any disadvantage to using smaller diameter tires

    Froggy, because you reduce the circumference of the tire you will also lower the ground speed for any given gear and increase the torque. This might have some disadvantages for ground engaging implements. You may tend to spin your wheels easier.

  4. #4
    Veteran Member
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    JD4320 with TNT, electric diverter, cruise control and air suspension seat.

    Default Re: Any disadvantage to using smaller diameter tires

    Robert,

    Saw the R1 24s were an option and are similar in size to the R4s. I know I don't want R4s becuase of the type of land I'm loking at in Cooke County (either black clay or sandy).

    The tractor I have now (an old IHC 2wd) has very tall narrow R1 tires, but I don't drive it in wet conditons. This will change when I purchased my new property and later get a 4wd one.

    Thanks for your input.

    Doyle

  5. #5
    Veteran Member
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    JD4320 with TNT, electric diverter, cruise control and air suspension seat.

    Default Re: Any disadvantage to using smaller diameter tires

    Jim,

    I hadn't thought of that. Another reason to go with larger tires.

    Thanks,

    Doyle

  6. #6
    Super Star Member
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    Aug 2001
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    Upper Midwest USA
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    JD 4300, JD X485 JD 4x2 Gator, JD 425, JD455

    Default Re: Any disadvantage to using smaller diameter tires

    You will feel the rough ground more with smaller diam tires than with larger diam.

    Its the reason I didn't go with the smaller tires and a Deere 855, rather than waiting for the Deere 4300. Demo'd an 855 and was not happy with travelling across a pasture.

    But your lower center of gravity may outweigh that as a disadvantage. [img]/forums/images/graemlins/wink.gif[/img]

  7. #7
    Gold Member
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    Apr 2001
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    Location
    Southeastern Mass
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    New Holland 1920

    Default Re: Any disadvantage to using smaller diameter tires

    froggy, while I don't think this will affect you, my NH 1920 with turf tires (which are 7 inches smaller in diameter) causes the backhoe to drag when loading/unloading on the trailer. Bill C

  8. #8
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    South Australia

    Default Re: Any disadvantage to using smaller diameter tires

    froggy,
    you will get the best traction from the tallest and widest tyre you can get. The amount of tire sitting on the ground on a large tyre compared to the small is very significant in regards traction. A large tyre will wear slower, and if you need weight at any time you can put more in the large tire hence more weight, with this last point i will also point out loading tyres lowers your centerer of gravity very significantly.
    GO THE BIGGEST MOTHERS THEY WILL GIVE YOU. [img]/forums/images/graemlins/wink.gif[/img]

  9. #9
    Veteran Member
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    Southwest PA
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    Deere 4710/reverser, JD 318 (still needs TLC), JD LT160

    Default Re: Any disadvantage to using smaller diameter tires

    One thought - Just so you are working with actual differences - you should try to find the true static loaded radius and rolling circumference of the exact tires in question (from the tire mfg. web site). Sometimes there's less (or more) difference than you might guess just going by the nominal tire size. I'm not sure what specific oem tires JD or NH are using on those models - but here are the numbers for the common Titan bias R1's:

    Static loaded radius / rolling circumference

    16.9/24 - 24/157
    14.9/28 - 24.8/163
    16.9/28 - 26/170
    16.9/30 - 27/176

    Actually for those exact tire models it looks like the differences work out pretty close to what you'd expect in radius (which will set the ground clearance) - but that can change depending on specific tire series.

  10. #10
    Gold Member
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    Sep 2004
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    Default Re: Any disadvantage to using smaller diameter tires

    The only advantage is the lower center of gravity and, if it is an advantage to you for some reasons, the 2" lower height.

    The major disadvantage is less traction and flotation. The 26" tire will have a smaller footprint due to the different radius of curvature. You will lose 2" of ground clearance and any mounted implement will lose 2" of ground clearance. The drawbar and pto shaft will be 2" lower and the angle of an attached pto shaft on a trailed implement may change.

    I wouldn't worry about the reduced ground speed, you should have enough gear choices to move up a gear if necessary, especially with a powershift. Your top road speed will be reduced by about 8% but on the other hand if you have an application where you need to go very slow you will be 8% slower.

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