fishpick
Platinum Member
I hate posts that never come to a conclusion (especially when folks offer input and advice)... because I always seem to the be the guy who finds said post for my question and never get an answer... so - here's where I'm at.
Went to a local Bobcat dealer right down the road - and talked "trade". I could unload my L4760 + FEL + front snow blower + Land Pride land plane for a CT2535 (or CT2540) + FEL + front blower + bobcat FEL attached land plane (this is so cool) + several other things + a Bobcat Zero Turn mower... and only pay a few grand out of pocket... I could ALSO trade in my older BX24 and get a additional attachment / options as well and be done - nothing out of pocket. So 2 tractors nets me a smaller tractor, added remotes on said tractor, some newer implements and a zero turn...
The thing is - the CT2535/40 chassis isn't THAT much smaller than my L4760... and the CT2540 weighs about as much - so - same issue with the yard (except R4's) - and life does not distill down / simplify to one unit - would have the zero turn... that ONLY mows. I did legit love the lever on the back of the Bobcat to raise and lower the lift arms when you are back there getting an implement on - I saw one of those on a Mahindra years ago - and can't believe it's on on every single tractor ever made since then.
So - while the deal is really good and I love the dealership (bought my first TC45DA years ago from them and that is still my favorite tractor ever) - I dunno that it changes much except I lose the small BX backhoe (gets used once every couple of years but when you have it - its great) and small loader if i need to get into tight spaces - and i get a zero turn to make mowing "faster".
So this got me reconsidering the tire swap math...
So - being a bit nerdy and attempting to quantify the choices based off input above and numbers... here's the numbers by the tire.
I then took the current ag tire and tractor weight - assuming a physical 3" wide contact patch of the tire on the ground - and did math... calculating the tractor weight per square inc of the tire - and then normalized to a numerical value I'm calling GDF - or ground destruction factor... This should give a mathematical representation of the impact of changing a tire on the amount of carnage endured on soft lawn surfaces - so here we go:
So for example - my current R1's - the front tire is 8.3" wide and I'm using the 3" wide contact patch - (yea I know lugs change it, load changes it, just relax) - that front tire has a contact patch of 8.3 * 3 = 24.9"... rear math is 14.9" * 3" = 44.7"
So - the L4760 is 4222 pounds + the loader on the front adds another whopping 1411# for a total of 5633. AND... I have Rim Guard in the rears... so let's say for just simplicity and sake of argument that plus me and any tools puts us at a conservative 6200#.
Now - again - just for simplicity - we are going to assume a 40/60 split on weight distribution with the loader on and bucket attached... it might be a little different but we will keep this ratio consistent for the sake of the comparison. That puts 40% of 6200 = 2480# on the front axle and 3720# on the rear... then take each axle number and divide by 2, beacuse there are two wheels per axle... so that's 1240 per wheel in the front and 1860 per wheel in the rear... and now we have all the numbers we need for some fun!
We can start calculating the Ground Destruction Factor that the tires have - again - omitting the impact of lugs which make it worse by effectively reducing the contact patch until the lug has bottomed out and not accounting for turning or other factors... This is just a straight line point A to B with loader on across wet lawn calculation...
First we need to know the pounds per square in the tire conveys to the surface via the contact patch.
And then we can normalize the R1's to assume their Ground Destruction Factor is GDF = 100 (by dividing it by itself * 100)... and then we divide all the other weights per tire by the standard we have in the R1 - so see how much more or less their GDF is - mathematically.
So - "math" says the R4's should be about 35% less destructive on the front and the R4's should be about 15% less destructive. Realistically the turfs are probably better than that by a fair bit and the R4's by a little bit - because - back to what I keep saying... "LUGS".
Thinking about the R3's - adding chains if needed - gives you the lugs.
So for about $3K - I can get a full set of R3's (probably not loaded) - and likely NOT destroy the yard to such a degree - and if needed - add a set of chains.
I am going to go look at a LX2610 and see what that looks like - It's a LOT lighter than the Bobcat - and when I do my GDF math on that with the R4's - it looks like they come out to about 25 PSI and a GDF of about 60 in the front and 62 in the rear...
I dunno - was a slow morning - spreadsheets are fun - now I gotta go do something useful...
Went to a local Bobcat dealer right down the road - and talked "trade". I could unload my L4760 + FEL + front snow blower + Land Pride land plane for a CT2535 (or CT2540) + FEL + front blower + bobcat FEL attached land plane (this is so cool) + several other things + a Bobcat Zero Turn mower... and only pay a few grand out of pocket... I could ALSO trade in my older BX24 and get a additional attachment / options as well and be done - nothing out of pocket. So 2 tractors nets me a smaller tractor, added remotes on said tractor, some newer implements and a zero turn...
The thing is - the CT2535/40 chassis isn't THAT much smaller than my L4760... and the CT2540 weighs about as much - so - same issue with the yard (except R4's) - and life does not distill down / simplify to one unit - would have the zero turn... that ONLY mows. I did legit love the lever on the back of the Bobcat to raise and lower the lift arms when you are back there getting an implement on - I saw one of those on a Mahindra years ago - and can't believe it's on on every single tractor ever made since then.
So - while the deal is really good and I love the dealership (bought my first TC45DA years ago from them and that is still my favorite tractor ever) - I dunno that it changes much except I lose the small BX backhoe (gets used once every couple of years but when you have it - its great) and small loader if i need to get into tight spaces - and i get a zero turn to make mowing "faster".
So this got me reconsidering the tire swap math...
So - being a bit nerdy and attempting to quantify the choices based off input above and numbers... here's the numbers by the tire.
Front Width | Rear Width | |
Ag (R1) | 8.3" | 14.9" |
Turf (R3) | 12.5 | 24" |
Industrial (R4) | 10" | 17.5" |
I then took the current ag tire and tractor weight - assuming a physical 3" wide contact patch of the tire on the ground - and did math... calculating the tractor weight per square inc of the tire - and then normalized to a numerical value I'm calling GDF - or ground destruction factor... This should give a mathematical representation of the impact of changing a tire on the amount of carnage endured on soft lawn surfaces - so here we go:
So for example - my current R1's - the front tire is 8.3" wide and I'm using the 3" wide contact patch - (yea I know lugs change it, load changes it, just relax) - that front tire has a contact patch of 8.3 * 3 = 24.9"... rear math is 14.9" * 3" = 44.7"
So - the L4760 is 4222 pounds + the loader on the front adds another whopping 1411# for a total of 5633. AND... I have Rim Guard in the rears... so let's say for just simplicity and sake of argument that plus me and any tools puts us at a conservative 6200#.
Now - again - just for simplicity - we are going to assume a 40/60 split on weight distribution with the loader on and bucket attached... it might be a little different but we will keep this ratio consistent for the sake of the comparison. That puts 40% of 6200 = 2480# on the front axle and 3720# on the rear... then take each axle number and divide by 2, beacuse there are two wheels per axle... so that's 1240 per wheel in the front and 1860 per wheel in the rear... and now we have all the numbers we need for some fun!
We can start calculating the Ground Destruction Factor that the tires have - again - omitting the impact of lugs which make it worse by effectively reducing the contact patch until the lug has bottomed out and not accounting for turning or other factors... This is just a straight line point A to B with loader on across wet lawn calculation...
First we need to know the pounds per square in the tire conveys to the surface via the contact patch.
PSI R1 | 49.7991968 | 41.6107383 |
PSI R3 | 33.0666667 | 25.8333333 |
PSI R4 | 41.3333333 | 35.4285714 |
And then we can normalize the R1's to assume their Ground Destruction Factor is GDF = 100 (by dividing it by itself * 100)... and then we divide all the other weights per tire by the standard we have in the R1 - so see how much more or less their GDF is - mathematically.
GDF R1 | 100 | 100 |
GDF R3 | 66 | 62 |
GDF R4 | 83 | 85 |
So - "math" says the R4's should be about 35% less destructive on the front and the R4's should be about 15% less destructive. Realistically the turfs are probably better than that by a fair bit and the R4's by a little bit - because - back to what I keep saying... "LUGS".
Thinking about the R3's - adding chains if needed - gives you the lugs.
So for about $3K - I can get a full set of R3's (probably not loaded) - and likely NOT destroy the yard to such a degree - and if needed - add a set of chains.
I am going to go look at a LX2610 and see what that looks like - It's a LOT lighter than the Bobcat - and when I do my GDF math on that with the R4's - it looks like they come out to about 25 PSI and a GDF of about 60 in the front and 62 in the rear...
I dunno - was a slow morning - spreadsheets are fun - now I gotta go do something useful...