Ag Tires vs. R4 Tires - Help Make a Decision Please

[LD1]

I meant that since R4 is wider and has more contact with the ground the ground pressure for a given weight of tractor would be less per square inch than an R1.

According to some, that would only be dependent on the PSI you were running in the tire. EG: 30PSI in R4's and 15psi in ags, some claim the R4's will have double the ground pressure.

Obviously I dont agree with that.

I'm done de-railing this thread.:thumbsup: Time to do something productive today

 

[SPYDERLK]

I meant that since R4 is wider and has more contact with the ground the ground pressure for a given weight of tractor would be less per square inch than an R1.

The only reason this is true is because of something you havnt stated. ... The lugs on AGs are comparatively sparse, but they are close enuf that carcass stiffness will still bridge between them. On firm ground where the lugs dont penetrate much the carcass doesnt touch down and presses on the lugs only. This results in very high ground contact force at the lugs.
,,,,Air pressure supports the weight of the tractor with a small contribution from carcass stiffness. Thus, regardless of tire width the contact patch area is inversly proportional to inflation pressure. R4s are harder carcass and higher inflation, therefore have less area touching ground and thus higher contact pressure averaged across the patch. The lugs on the AGs are their compaction issue -- not their width.
larry

 

[MHarryE]

The pressure thing is a law of physics and I've confirmed it with pressure sensitive film being driven over with tires inflated to various pressures, but that was by controlled test. Soil type, bar profile, and depth of bar penetration all are significant in the real world. Like today doing loader work in sloppy mud with frozen ground somewhere underneath. With the bucket full the tires sank a lot deeper than with the loader empty although the tire pressure never changed.

For my CUT the R-4 tires have about 75% more load capacity per tire than the ag tires offered. When I did some calculations I found that my fronts, if R-1, would be overloaded at max loader lift but the R-4s are well within load rating. I used ratings from Titan's book since Titan tires are listed as standard on my tractor for both R-1 and R-4.

 

[Chilly807]

The pressure thing is a law of physics and I've confirmed it with pressure sensitive film being driven over with tires inflated to various pressures, but that was by controlled test. Soil type, bar profile, and depth of bar penetration all are significant in the real world. Like today doing loader work in sloppy mud with frozen ground somewhere underneath. With the bucket full the tires sank a lot deeper than with the loader empty although the tire pressure never changed.

For my CUT the R-4 tires have about 75% more load capacity per tire than the ag tires offered. When I did some calculations I found that my fronts, if R-1, would be overloaded at max loader lift but the R-4s are well within load rating. I used ratings from Titan's book since Titan tires are listed as standard on my tractor for both R-1 and R-4.

I found out the hard way that my front R1's need max inflation pressure if I'm doing any serious loader work. They delaminated and developed bulges in the sidewall. I replaced them, with tubes installed this time, and run 36 psi all the time now.

Sean

 

[LD1]

In the "real" world, skinny tires make deeper ruts than fat tires regardless of whatever psi you are running them at. Thats the point. R4's are wider than the R1 counter parts. There-fore offer more flotation and less rutting.

Now on a concrete pad, where tires stand "tall" on their lugs and the ground wont move out from under them at all, maybe it has merit.

 

[SPYDERLK]

The pressure thing is a law of physics and I've confirmed it with pressure sensitive film being driven over with tires inflated to various pressures, but that was by controlled test. Soil type, bar profile, and depth of bar penetration all are significant in the real world. Like today doing loader work in sloppy mud with frozen ground somewhere underneath. With the bucket full the tires sank a lot deeper than with the loader empty although the tire pressure never changed.
For my CUT the R-4 tires have about 75% more load capacity per tire than the ag tires offered. When I did some calculations I found that my fronts, if R-1, would be overloaded at max loader lift but the R-4s are well within load rating. I used ratings from Titan's book since Titan tires are listed as standard on my tractor for both R-1 and R-4.

With the greater load the tire deflected more causing more area in contact ... so the heavier load was supported w/o any significant pressure change. It is counterintuitive that pressure does not rise appreciably with higher load.
larry

 

[crazyal]

I like my Ag tires. They work well int the woods getting traction in the dirt. I do drive across my lawn and as long as it's not wet the lawn bounces right back. I have the R4s on my BH and they work fine but not as much traction. The next time I need to replace them I'm thinking of going to Ag tires. But as others have said, R4 tires are better when it comes to resisting punctures. They are also better for loader work as they can handle a full load in the FEL better. My Ag will squat out like no tomorrow even at the max rated pressure. If the ground is soft the Ags will get better traction but when I turn the wheels they distort pretty badly.

 

[SPYDERLK]

In the "real" world, skinny tires make deeper ruts than fat tires regardless of whatever psi you are running them at. Thats the point. R4's are wider than the R1 counter parts. There-fore offer more flotation and less rutting.

Now on a concrete pad, where tires stand "tall" on their lugs and the ground wont move out from under them at all, maybe it has merit.

This is not an indication of compaction, but of the path consolidated soil must take to move away from the tires pressure on it. With equal inflation the patches of R4 and R1 are equal area. However, the R4 contact patch is short and wide whereas the R1 patch is long and narrow. The soil moves in all directions in response to the pressure. With the narrow tire, down and sideways is the shorter/easier distance. With the wider tire, down and forward/backward is the shorter and easier route. Putting the tires in motion the wide tire runs a "bow wave" pushing dirt forward and down, while the narrow tire displaces the dirt more to the side. The wider tire leaves a wider rut thereby affecting more soil. The narrow tire leaves a deeper rut.
Neglecting lugs and talking tire profile only Id put the R4 as the more effective compactor. Considering its real world smaller diameter, stiffer carcass, and higher necessary inflation in relation to the equivalent R1 only worsens the compacting.
,,,Factoring the lugs back in makes R1s more able to compact firm ground as mentioned in an earlier post.
larry

 

[Chilly807]

Think about turf tires as on golf course machinery. Usually quite wide so as to spread the machine weight over a larger area and reduce the pressure per square inch on the ground.

My excavation guy told me once that his Hitachi excavator exerts a track pressure of 7 pounds per square inch on the ground. Probably explains why I nearly buried my car driving on the tracks the excavator left while he was digging my well. The car weighs a lot less than the excavator, but has a contact patch many times smaller.

Sean

 

[Gary Fowler]

I like my Ag tires. They work well int the woods getting traction in the dirt. I do drive across my lawn and as long as it's not wet the lawn bounces right back. I have the R4s on my BH and they work fine but not as much traction. The next time I need to replace them I'm thinking of going to Ag tires. But as others have said, R4 tires are better when it comes to resisting punctures. They are also better for loader work as they can handle a full load in the FEL better. My Ag will squat out like no tomorrow even at the max rated pressure. If the ground is soft the Ags will get better traction but when I turn the wheels they distort pretty badly.

I suppose it has to do with tire size but my LS P7010 with Ag tires doesn't squat at all with fully loaded bucket. On hard ground if feels like I have Cat tracks on it as I can feel each lug as it hits the ground but no tire squat is evident and I have reduced the air pressure a bit from max. But then again, my front tires are as large as many CUT rear tires and with a 3500 pound lift capacity, it will lift most CUTs off the ground.