tire school

[gerard]

Can someone explain what the front and rear tire #'s refer to? I'm familiar with car tires but the #'s don't seem to translate. Also when buying rims is it as simple as insuring the # of bolt holes are equal or do you have to measure the spacing from center. ie Is there any commonality between manufacturers? Tires 101 would be appreciated. (I missed out on buying 4 new turfs mounted on rims for $400 at auction due to lack of knowledge !! Not much of a bargain if they don't fit!!)

 

[MChalkley]

The numbers on my tractor tires are 12-16.5NHS (front) and 19.5LR24 (rear). Front first: the 12 means the section width of the tire in inches. Sometimes this is the same as the tread width, usually it's a little wider. The 16.5 means the rim size is 16.5 inches in diameter. You also need to have the correct rim width, but you'd need the manufacturer's data sheet for the tire to find that out. The NHS means Non Highway Service, which means low speed only and sometimes, depending on the manufacturer, means skid steer use only, meaning the tires don't have the sidewall strength to allow use on a turning axle. Now for the rear: The 19.5, again, is the section width of the tire in inches. The L means low profile, meaning the ratio of height to width is lower than would be the case on a typical ag tire. The R means radial, as opposed to bias ply. The 24, again, is the rim diameter in inches.

Does this help? There are several types of dimensions on tires - if the ones you're speaking of are different, give us an example.

Mark

 

[Anonymous Poster]

To clarify a bit further, the first number is the section width of the tire measured "cheek-to-cheek" across the outside of the tire at the Top of the tire when the tractor is parked. It will be wider at the bottom due to the tire bulge. The tread width across the tread bars is always less because the sidewall bulges beyond the tread bars. The several numbers in the tire size designation depend on whether it is an R1 or other tire, a bias-ply, or a radial. They are all different. When thinking about a given tire size, it is safest to refer to a catalog from a tire manufacturer or the tables of the Tire and Rim Association to find out the exact dimensions and required rim size. Radial tires on your car or truck and on large farm tractors follow this scheme---Example: Typical car tire size 185/70R14 means the width of the tire is 185 mm, the ratio of the sidewall height to the section width is 70 per cent, R means radial, and it is on a 14 inch diameter rim. I know it seems screwy to have the first number in millimeters and the last number in inches, but that is the world standard way to designate radial tire sizes be it for cars, trucks, or tractors. Go Figgar.

 

[gerard]

That helps some. I'll have to check my tires when I get home and I'll post what they are as they seem to be missing a third #. I have R1's on an L2500. I guess what I'd like to know is the easiest way to figure out if a turf for example should have the exact same #'s as the Ags or do I just have to insure the ratio for the circumference front to rear is the same? (4wd)

 

[Anonymous Poster]

Typical bias ply R-1 (ag), R-4 (Industrial), and SOME turf tires only use 2 numbers, the first being the tire section width and the second being the rim diameter. From this alone you cannot determine what the outside diameter of the tire or the rolling circumference is. You must go to a tire catalog to look them up. Turf tires sometimes use this same designation, but more often they use 3 numbers such as 36x13.50-15. Here the numbers are 36 inch nominal outside diameter, 13.5" wide tire section width, and 15 inch rim. The essential requirement when considering changing tire sizes is to have the rolling circumference ratio be as close to the original as possible. This is the same as the gear ratio of the front axle speed to the rear axle speed that is built into the gear train that drives the front axle. To insure that you get this right, it is necessary to refer to the detailed catalogs from the tire manufacturers (Goodyear, etc.) or to the tables printed by the Tire and Rim Association.

 

[MChalkley]

Or, if for some reason you're considering changing all 4 tires, you can just make sure the ratio of front tire rolling circumference to rear tire rolling circumference stays the same.

Or, even easier, if you can get the number for the mechanical ratio between the front and rear axles for your tractor (i.e. the number of times the front axle turns for each turn of the rear axle), you can then multiply the rolling circumference of the front tires by this number and the result should be 0% to 3% greater than the rolling circumference of the rear tires. It must never be less, or you risk killing yourself and/or your tractor.

Mark

P.S. Jack - do I pass or fail? /w3tcompact/icons/smile.gif

 

[gordon]

Hold on guys I need to enroll in this school. For something as important as tires my knowledge is very very shallow. That what always worried me about switching brands and types. Lack of knowledge and trust in the tire salesman. Sorry to all the salesman out there I don't trust any of you not just tire salesman. Anything that might be commission related that is---and sorry saleswomen too.

Gordon

 

[Anonymous Poster]

P

 

[richh]

LOOKS LIKE TIRES MOVED ON ME. Mark did you get the info on where to get those michelin from?? I also posted the sizes of the fronts on buying a kabota, I think?? to many headings on here.


Rich

 

[MChalkley]

RichH - Yes, I got it. I thought I replied to the email message, but maybe not. Anyway: Thanks! I'm going to call them Monday. I'll let you know.

Yeah, you're right: there are two tire threads (at least) going on here.

Mark

 

[jgh]

NH dealer told me today that NH 4wd tractors are set so that the front runs 5% faster than the rear.

Seems like a large differential (no pun intended) to me.

Jim

 

[MChalkley]

Well, that's not too much, really. Some manufacturers do say that 0% to 5% lead is ok. Some even say that 0% isn't ok, that you need at least 1% lead. But they all agree that it must never be negative (lag). My L4310HST is set up at about 3.7% lead, but when I switch to the Michelin XM27's up front like the ones I have on the rear (but a different size, obviously), it'll be 0.3% lead. It'll be interesting to see if I can tell any difference. It should be easier to take in and out of 4wd, but I doubt I notice any other differences.

Mark

 

[richh]

Mark what is the overall wdith in the rear of your tractor with the michelins?? Do you have any trouble hooking up any other tools be side the backhoe? IM realy leaning to the same size that you are running the 19.5 but dont want any trouble hooking up the tiller or the winch. and just to recap the 19.5 and the 11LR16 will work toghther right??
thanks Rich

 

[MChalkley]

Rich, I think it's right at 75", counting the sidewall bulges. The tread width is still just under 72", so a 6' box scraper will just cover the tracks if it's centered and I'm going straight. I'll try to remember to measure it tomorrow. I've got another lot to rough grade. I'm not looking forward to the 90+ they say the temp is going to be, though.

I've not had the slightest trouble with anything other than the backhoe. If you've got over 2" of clearance behind the tires with the implement, it'll be fine with the new tires. FWIW, the Freedom Hitch adds 4" or 5" of clearance, so I you use them, any clearance problems that you might have had on 3-point mounting implements go away.

Yes, the 19.5LR24's and 11LR16's are perfect matches, at least on the L-series HST's. You need to find out what the mechanical ratio between the front and rear axles is on the tractor you're looking at to be sure. Call Kubota to find out and let me know - then I can tell you for sure.

Mark

 

[W5FL]

This is the first time I saw a new set of Tractor Tires. I thought they were supposed to be cracked between the bars. /w3tcompact/icons/smile.gif

Seriously how long will Tractor Tires hold up if kept garaged when not being used?

Tractor tires seem to last a long time. Has anyone had to replace them that DID NOT do much highway driving?

 

[MChalkley]

Richh, I ordered a set of Michelin XM27 11LR16's from your dealer up in Michigan this morning. Nice folks and a great price, too. Thanks for the help. I really appreciate it! You saved me $70 per tire, even after I pay $15 each to ship them!

Mark

 

[richh]

Well let us know how those babbys work for you!! IM still waiting for the tractor. I thought I would try selling my 1910 on line here befor the new one comes but IM haven trouble getting the pitc. to load. Well IM going to go give it a shot.
RICH