M59 front axle and front wheel rim load rating

[RjCorazza]

Loaded rear tires don’t reduce front wheel loading. Only additional weight rearward of the rear axle does.

The OP should definitely be using substantial rear ballast.

 

[rScotty]

Not one to argue with answer directly from Kubota customer service, but I thought the front axle max load was a bit light in their response since each wheel, at 4140 Lbs, can almost fully load the front axle with max rated load of 4410 Lbs. The M59 loader max lift is 3968 Lbs at pivot pin so add in some front end weight from engine and your at the 4410 Lbs.

Guess 10 ply is more than sufficient and I'll be making sure I always keep the machine greased to minimize wear and tear.

I think I will argue. I think we should use worst case conditions rather than max axle load rating when figuring how to prevent tire & wheel failure. Kubota's rated breakout force is a higher number. Breakout is 5961 lbs. Combine that with whatever degree of side slope it sees, and that is your wheel and sidewall stiffness requirement.

My own opinion - not from any calculations - is that the Titan HD that Kubota uses is an excellent premium tire even if it only has an meager 8 ply rating. It performs so well that In 20 years now, failures like yours are rare.
But your use miles back in the woods with a grapple puts even more force on the rims. If I was doing that type work or using a different brand tire I would go for a higher ply rating...especially since I like to run fronts at less than 60 psi.
YMMV,
rScotty

 

[M59]

The OP should definitely be using substantial rear ballast.

I'll partially disagree with DarkBlack in that the tractor has two centers of rotation. Front axle and back axle. If large load ahead of front axle then any weight behind the front axle acts as a counter balance. The further back the weight is behind the front axle the greater the lever. Weight behind the rear axle has the greatest lever and begins to shift weight onto rear axle.

The M59 backhoe is 1925 Lbs without bucket. I run a special made quick attach adapter and the KX series buckets which are much heavier than the stock M59 pin on buckets. Lots of ballast back there.

I don't see how I can have any greater ballast on rear than I presently do.

 

[M59]

I think I will argue. I think we should use worst case conditions rather than max axle load rating when figuring how to prevent tire & wheel failure. Kubota's rated breakout force is a higher number. Breakout is 5961 lbs. Combine that with whatever degree of side slope it sees, and that is your wheel and sidewall stiffness requirement.

My own opinion - not from any calculations - is that the Titan HD that Kubota uses is an excellent premium tire even if it only has an meager 8 ply rating. It performs so well that In 20 years now, failures like yours are rare.
But your use miles back in the woods with a grapple puts even more force on the rims. If I was doing that type work or using a different brand tire I would go for a higher ply rating...especially since I like to run fronts at less than 60 psi.
YMMV,
rScotty

rScotty,

Not as rare as you might think. Smokeydog has suffered similar front end tire deflation events with his M59.

Lesson learned so I will find the highest load index within the 10 ply tire offerings ( load range E ) and use bolt in brass valve stems AND now have a spare mounted tire so I can change out a tire, in the woods, if similar broken bead/ flat tire happens.

 

[DarkBlack]

I'll partially disagree with DarkBlack in that the tractor has two centers of rotation. Front axle and back axle. If large load ahead of front axle then any weight behind the front axle acts as a counter balance.

You’re confusing tractor balancing , with load on the front axle(s).
Weighted rear tires and any mass, between the rear axle and front axle helps prevent rotation about the front axle(s) , but does nothing to lower the force on the front axle(s).
Loads forward of the front axle, simply transfers rear tire weight onto the front axle(s).

Only mass behind the rear axle, actually lifts weight off of the front axles, by the rear axle being an axis of rotation. It’s physics.

 

[RjCorazza]

DarkBlack has it right. Loaded rears do help keep the back end planted, but will not remove any weight off of the front axle (zero).

 

[mikester]

Kubota Customer Satisfaction just replied back to my email to them from earlier today so I'm posting it for those with the M59 machine.

Here is their contact info if you want to go that route
https://www.kubotausa.com/contact Then choose “Send us your question”

My Q to them:
Please provide information on front axle load rating for M59 TLB? I've looked through Operator and Workshop manuals and found no info on front axle rating. I’ve contacted my local Knoxville dealer with no result.

Also looking for front wheel rim ( size 16.5 x 8.25 by 8 bolt ) load rating so I can choose between 10 or 12 ply tires to match rim load rating.

Their answers:
Thank you for contacting Kubota Customer Satisfaction. I have included below the information you have requested.

• Maximum permissible front axle load--lbs (kg): 4410 (2000)
• Kubota tests wheel and rim combinations. The combo we market uses a Titan 4393D1 Tire on a 16.5 x 8.25 rim with a max load rating of 4140 lbs @60 PSI. The Titan 4393D1 is an 8 Ply.

Kind Regards,
Kubota Customer Satisfaction

Sounds like the TLB at 8,300lbs the front axel is at it's max load rating before adding another 3,900lbs load on the bucket pins.

With my ~1,200lbs cab I'm way over

 

[Smokeydog]

About 10-15 years ago had a rash of valve stem failures from atvs, tractors, vehicles and trailers. Switched to bolt-in style where I can. Haven’t had one of them fail since. Nothing ruins the momentum of the day like flat tire.

 

[RjCorazza]

About 10-15 years ago had a rash of valve stem failures from atvs, tractors, vehicles and trailers. Switched to bolt-in style where I can. Haven’t had one of them fail since. Nothing ruins the momentum of the day like flat tire.

That's about the same time frame that I had several rubber valve stem failures, mostly due to cracking and dry rot after a year or so.
I also switched everything over to metal bolted valve stems.

 

[rScotty]

rScotty,

Not as rare as you might think. Smokeydog has suffered similar front end tire deflation events with his M59.

Lesson learned so I will find the highest load index within the 10 ply tire offerings ( load range E ) and use bolt in brass valve stems AND now have a spare mounted tire so I can change out a tire, in the woods, if similar broken bead/ flat tire happens.

I've seen my share of beads coming off rims. I still say it is rare in normal use.
Just last year I slipped a bead on one of a set of fairly new Titan rear tires on the jD310. I'd have thought that was impossible. Yes, I was abusing it - on a hillside slope lifting a large downed tree over a creek with the extenda-hoe at full extension....Still, it surprised me to roll a rear tire off the rim.
Let us know what tire you decide on.
rScotty