Lead/lag ??? on Grand L series

ttowne66 · Feb 1, 2006

Hey Guys

Reading thru some of the old Glenmack's tire swap threads and found out that the 3830 and up may not have the correct lead. Possibly needing a larger front tire to make up for the issue. Anyone know any specific details to this. Thanks.

Tom

CT_Tree_Guy · Feb 3, 2006

Hiya Tom -

In my opinion, this is an excellent point that you just raised, and one that doesn't get nearly enough attention.

I'm short on time right now, but - short version: the stock R4's on most if not all of the Grand L's are WAY off on lead/lag. 0-6% lead is acceptable, and ANY amount of lag is unacceptable. The 5030 with stock R4's has over 5% lag, which is off-the-charts bad. If I recall, the other GL's were as bad, or almost. (The ags were fine). For that reason and others, I went with turfs that gave me about a 3% lead (if memory serves), and a set of XM27's with about a 1% lead.

Here are two threads on the subject:

New wheels for L3130?

L series tire question and problem.

John

ttowne66 · Feb 3, 2006

Tree Guy

Thanks, somehow I knew you would be the first to post on this issue! For my peice of mind, I really need a source that has the actual gear ratio information so the calculation can be performed. There is nothing in my owners manual on gear ratio. The overall diameter of the stock R4's is 30.3in. I imagine you could go up to the next size R4 12-16.5 NHS which is 32.7 in overall diameter and 12in wide(maybe too wide for the stock rim). Without knowing the ratio though, this may or may not be big enough. I checked my clearance to the loader frame and there is enough for the 32.7 diameter tires. This may not be the case on the 3830, 3430 or 3130 though!

Here are the Titan Tire specs

http://www.titanstore.com/store/agricultural.html

click on backhoe/skidsteer, then on HD2000 II

Tom

2

SnoFalls · Feb 3, 2006

I also would like to hear the gear ratio(s) (both at the diffs and in the trans). Also, do the portals at the front have a reduction ratio?

CT_Tree_Guy · Feb 3, 2006

Hiya Tom -

The mechanical ratio for all the Grand L's is 1.5640; (snofalls), this should be the only tractor-related info you need to calculate the lead-lag ratios. Make sure you use the "rolling circumference" of the tire(s) in question to do the calculations; you won't get accurate results if you work from the "overall diameter". Rolling circumference is a much more accurate measurement of how much ground the tire will cover in one revolution when it's inflated, loaded, etc. Most every tire manufacturer will list the rolling circumference of all their tires on their website. I also have two different lead/lag worksheets that I can post if y'all need them.

And here's another good link: Picking up Glenn's Work - R1W Tires Grand L's

Thanks slowzuki for putting together this "master thread" (sort of a "Glennmac's Greatest Hits" on tire info).

John

AB4D · Feb 3, 2006

Tom,

Check out Tractorsmart.com they have a section on this subject.

Jim

RFB · Feb 3, 2006

John,

I read all of the tire threads, and still did not achieve a solid understanding. I have yet to take delivery of my 5030; it currently has r4's, and the dealer said (at my request) that he would switch them to r1's at no change in cost.

I am going to use this tractor in a strictly ag, dirt/gravel road, and snow-moving environment. No turf or lawns to worry about, and no paved roads.

My question is: Should I stick with the Kubota r1's, or should I tell the dealer to get the Michelins(and what model?), and if I do, will it be a straight size for size swap with no mods necessary for size of tire or rim?

Thanks again,

RFB

ttowne66 · Feb 3, 2006

CT and AB4D Thanks a bunch...Time to do some quick math now!

CT_Tree_Guy · Feb 3, 2006

RFB -

I don't have as much info at my fingertips as I "should" about wheel sizes and tire sizes for the 5030. It got pretty complicated as I went through all the choices - stock R1 ags, R3 turfs, R4 industrials and Michelin radials.

The Titan turfs that are on my tractor now are 29 x 12.50 -15 (29" diameter, 12.5" wide on a 15" wheel) on the front, and the rears are 44 x 18 - 20. My Michelin XM27 radials are 11LR16 on the front (11" wide, 16" wheel) and 19.5R24 on the rear. There is a slightly narrower XM27 for the rear (16.5? 17.5?) that also gives an excellent lead ratio.

Bottom line: the Michelins are insanely expensive (almost $2K including tax just for the tires), and when Kubota says they have "too much traction"; for all I know, they might be right. If your dealer will swap the R4's with the terrible lag ratio for the stock ags (9.5-16 fronts and 14.9 -26 rears) with an excellent lead ratio of around 1-3%, that might just be the way to go. The main reason I went with the Michelins was to keep ground pressure to an absolute minimum, but since you don't have those constraints you might just be wasting your money. The radials might last longer than bias ply, but maybe not by enough to make it worthwhile.

Also, your dealer would probably not be able to get them for you - you'd probably have to go directly through a tire distributor, as I did. Here in the Northeast, last time I checked there was only one distributor, Pete's Tire Barn. I ordered the extra wheels from a Kubota dealer, had them shipped to Pete's, then picked up the mounted tires from one of their distribution outlets in Torrington CT. All in all, quite a pain in the you-know-what.

Hope this helps more than hurts, but to me, those stock ags are starting to look pretty good.

Good luck, and feel free to ask any more questions you might have,

John

RFB · Feb 3, 2006

John,

Thanks a lot. You are always prompt and informative, and I do not want to wear you down.

But...

You mentioned 9.5-16 fronts and 14.9 -26 rears, and I see those numbers as the spec for the 5030. The dealer said he is looking at 13.6 x 28 for the rears. All of these numbers are greek to me. What practical (positive/negative/neutral) effect will there be in changing from 14.9 x 26 to 13.6 x 28 rear tires?
(And just what do those numbers mean?)

John, thank you for all your help.

RFB

ttowne66 · Feb 3, 2006

Guys

With the knowledge gained by Tree Guy and AB4D, I have come up with the following solution
1) The Titan 12-16.5 NHS 49E3J7 fits right in the slot at 4.6% lead for the Grand L's with 17.5-24 firestone rear tires as they have a r.c. of 145. in fact, any tire that has a roling Circumfrence between 93 to 97 inches falls in the range.
2) The 3130 and 3430 are right at 4.6% with the stock set-up.
3) The scary part of this is that the stock set-up for 3830 thru 5030 tractors with industrials are all operating with almost a 2% lag condition. /forums/images/graemlins/confused.gif

CT_Tree_Guy · Feb 3, 2006

What practical (positive/negative/neutral) effect will there be in changing from 14.9 x 26 to 13.6 x 28 rear tires? (And just what do those numbers mean?) 

RFB -

The 14.9" and 13.6" are the width of the tire, measured, I think, at the widest part of the sidewall. The 26" and 28" are the diameter of the wheel/size of the "hole" in the tire. A 28" wheel vs. a 26" wheel would mean that the 28" tire would be "shorter" than the one on the 26" wheel, as measured from the ground to where the wheel starts. This would probably result in a harsher ride - not that we're talking about Lexus' here - but the tires are all the "suspension" you've got.

And of course, you'd also have to run the numbers on the rolling circumference of the 13.6 - 28 tire compared to the 14.9 - 26 to make sure it would still give you a "good" lead ratio - BUT - If it were me, that comparison would be for purely "academic" purposes. I'd insist on the wider, "stock" size of 14.9 - 26, and ask him some very pointed questions about why he's going against Kubota's recommendations. Sounds to me as if he's got an oddball set of wheels and tires that he's looking to get rid of, at your expense. Others might disagree, but they sound a little too skinny for my taste (and the dealer is starting to sound a little too "slippery", too).

Keep us posted, and again, don't hesitate to ask me any questions. A) You're not "bugging" me, and B) I'm sure I'm going to need your help before long. /forums/images/graemlins/smile.gif

Good luck, John

KennyV · Feb 3, 2006

Several years ago I was considering this same thing… Larger footprint while keeping the ratio right… I switched from factory Good Year R1 AG front 8.3-16 and rear R1 Firestone 14.9-24 To Titan R3 Torc Trac front 12-16.5 and rear 16.9-24. Had to get new wider rims for both front and rear, this gave me a 1.5 percent lead and it couldn’t have worked out better. The big front tires are great for loader work, they are perfect for mowing with no turf damage and larger tires gave a MUCH softer ride. These turf tires also have incredible traction in snow. KennyV.

CT_Tree_Guy · Feb 3, 2006

Tom -

Interesting stuff, thanks. I had never run the R4 numbers on the other Grand L's and never knew that the 3130 and 3430 had good ratios. I'm more than a little surprised at Kubota for not offering "properly" sized R4's on the larger L's. I was told by several very reputable sources that any amount of lag is "totally unacceptable", and it makes sense when you think about it. If the fronts are just being pushed along by the more "powerful" rears when in 4WD, how much good are they actually doing?

I was also appalled, and felt somewhat insulted even, when a Kubota rep suggested that I overinflate the fronts to try to compensate for the crummy lag ratio. Not very good advice in my opinion - but hey, we all say things we might later regret. Plus, tractor manufacturers have a lot of "real world" constraints to deal with when setting up contracts with suppliers, and I guess they did the best they could do. And they still build a better tractor than I ever could in my wildest dreams, so I certainly forgive them a little boo-boo or two.

Sounds like your homework is going to pay off though - good job.

John

ttowne66 · Feb 3, 2006

Tree Guy

I certainly couldn't have calculated this without the info you provided so thanks to you! Now the next question....as the Titan 12-16.5 NHS 49E3J7 recomends a 9.25 wide rim, will these wider Titans fit on the stock rim? To go along with your thoughts on the 2% lag condition on stock set-ups of 38-5030's here is an interesting quote form tractorsmart.com.

Proper tire sizing/matching on front wheel assist tractors is a function of insuring that the front axle 'lead" specification is kept within acceptable design and operational limits. Front axle lead (or slippage) is necessary on front wheel assist tractors in order to realize the benefits of front axle tractive assistance. Desired front axle lead is expressed as a positve increase in front axle speed over that of the rear axle, usually in terms of percentage (ideally +1%-+5% for most front wheel assist tractors). Lead percentages outside of this range will lead to problems such as accelerated tire wear, difficult steering, loss of tractive assistance from the front axle as well as increased drive train wear with premature failures. Negative lead (or slippage) will, from the outset, totally negate any potential advantages offered by front wheel assist.

/forums/images/graemlins/crazy.gif

CT_Tree_Guy · Feb 3, 2006

Negative lead (or slippage) will, from the outset, totally negate any potential advantages offered by front wheel assist. 

Now there's something you won't see in the Grand L brochure. /forums/images/graemlins/tongue.gif

Tom, as for whether or not the Titan 12-16.5's will fit on the stock rim, I'm reminded of one of Clint Eastwood's best lines ever, from "Magnum Force": "A man's gotta know his limitations". /forums/images/graemlins/smile.gif I'm really not sure if they will, and I'm not even sure what width the stock rim is. My gut feeling is that they should be fine, but I'd strongly recommend finding out the width of the Kubota rim and asking Titan for their opinion; they're sure going to know best.

Thanks for all the good info, and I must say, it's been reassuring to know that I'm not the only one who cares about this kind of thing. Sometimes I worry a little about myself. /forums/images/graemlins/laugh.gif

John

ttowne66 · Feb 3, 2006

Ok

I just went out and checked the rim size and it is actually 9.75 which is the exact reccomended width for the larger 12-16.5 NHS 49E3J7. So now the question of why kubota would intentionaly put on tires that are lagging?? You can't tell me they did not know! Everything is there except for the tire! I have no idea of why companies insist on doing the wrong things for extra profit. Just add the extra cost into the **** machine!

LRH · Feb 5, 2006

( What practical (positive/negative/neutral) effect will there be in changing from 14.9 x 26 to 13.6 x 28 rear tires? (And just what do those numbers mean?) 

RFB -

The 14.9" and 13.6" are the width of the tire, measured, I think, at the widest part of the sidewall. The 26" and 28" are the diameter of the wheel/size of the "hole" in the tire. A 28" wheel vs. a 26" wheel would mean that the 28" tire would be "shorter" than the one on the 26" wheel, as measured from the ground to where the wheel starts. This would probably result in a harsher ride - not that we're talking about Lexus' here - but the tires are all the "suspension" you've got.

And of course, you'd also have to run the numbers on the rolling circumference of the 13.6 - 28 tire compared to the 14.9 - 26 to make sure it would still give you a "good" lead ratio - BUT - If it were me, that comparison would be for purely "academic" purposes. I'd insist on the wider, "stock" size of 14.9 - 26, and ask him some very pointed questions about why he's going against Kubota's recommendations. Sounds to me as if he's got an oddball set of wheels and tires that he's looking to get rid of, at your expense. Others might disagree, but they sound a little too skinny for my taste (and the dealer is starting to sound a little too "slippery", too).

)

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Per the 2005 kubota retail price sheet; the tires included in the base price (5030) are 9.5-16 AG front with 14.9-26 Hi-Power Lug AG rear. A second ag choice is the same tires front with 13.6-28 R1 AG as a no cost option. Both rear tires are virtually the same rolling radius so front tire does not change. Then of course they offer R4's, turf, and Galaxy turf.

bugstruck · Feb 6, 2006

Hi John,

I can verify the 3130 has good lead on R-4's. I'm at 3.5% with Firestone 420 70-24 (136" R.C) and Titan 10-16.5 NHS #4123C8 (90" R.C). Assuming of course, I did the math right /forums/images/graemlins/tongue.gif You guys had me wondering though.. Take care John.

mojavedesert · Feb 7, 2006

Having read the above thread and being the owner of a new 3830 with r4's, I was concerned enough to call my dealer who then refered me to the Kubota rep in CA. The rep was forwarded a link to this thread along with links to the Tractorsmart calculation page. Bottom line is the rep was no help whatsoever and in fact somewhat curt in his response---
-(he said Kubota has done the engineering for correct lead and this tire setup is approved while any other setup( like the larger front tire suggested by ttown66) is not and would(presumably) affect the warranty of the tractor. He was not kind to "the self appointed experts on the forums". There was a thread a while back about the r4 fronts having a clearance issue with the front end loader on tight turns---I wonder if this could have led to the use of a smaller tire on the front? Since Kubota was so dismissive, I am wondering how to find out more about this. What do you other affected owners think?
K