Tires on my tractor not to manufacturer's spec

[ROUSTABOUT]

But nobody makes a 26.75 or 27.25 tire.

They need to say 27 on the side and you are fine

Your talking tire size. I mean overall gear ratios. There can be a lot of variance in tire size and it will work fine. I'd still never use 4x4 on any hard surface at all. Only to go straight through a wet spot. I've already replaced front gears in a guys tractor. Replaced a broke axle on another, replaced some triangle broke thing in a new Holland. There's a fella on here getting broke front end things repaired. All wheel drive you can but four wheel drive is different.

Speed = rpm x rtr ÷ 168 x rgr. That formula will tell you. Just find your final ratios and plug the numbers in.

 

[90cummins]

I hear you.

But tire size & pressure can have a huge impact on drive line stresses and failures.
Engineers have what is called a 4 square gear tester where 4 gears are installed on 2 shafts and preloaded with a jack screw that pre-loads the gear faces.
Large gear sets can be tested with simulated torque loads using a small electric motor to turn the assembly. Years of use can be simulated in weeks.
There is no reason for broken gears or axles due to miss-matched tire options from the manufacturer. With all the tire size selections available (turf & agg) the manufacturer can easily make any front/rear tire size work without conflict with proper gear choices.
Many tractor owners are not aware of the damage caused by torque binding and driving in 4wd continuously.
It’s easy with all 4 tires being equal rolling diameter.
My Ford 1720 came with factory turf tires that were grossly miss-matched. On dirt & snow the fronts were trying to walk away from the rears. If I be was to coast mmgoing straight in 4wd it would come to a whining stop within 10 feet.
I resolved this by slowly reducing the air pressure in the front tires until I could drive on blacktop in 4wd with no binding.
Next I marked the front tire’s where they contacted the floor and rolled it exactly 1 turn. I then measured the distance between marks and used Tire Rack’s website to find an auto tire with the correct diameter. I bought 2 radial snows after determining what I needed then fine tuned the f&r pressures until I could run down the road in 4wd with no binding.

Didn’t intend to turn this thread in another direction but I felt it was a good opportunity to bring awareness to tire size and how to identify a miss match & calculate a solution.
90cummins

 

[LouNY]

I hear you.

But tire size & pressure can have a huge impact on drive line stresses and failures.
Engineers have what is called a 4 square gear tester where 4 gears are installed on 2 shafts and preloaded with a jack screw that pre-loads the gear faces.
Large gear sets can be tested with simulated torque loads using a small electric motor to turn the assembly. Years of use can be simulated in weeks.
There is no reason for broken gears or axles due to miss-matched tire options from the manufacturer. With all the tire size selections available (turf & agg) the manufacturer can easily make any front/rear tire size work without conflict with proper gear choices.
Many tractor owners are not aware of the damage caused by torque binding and driving in 4wd continuously.
It’s easy with all 4 tires being equal rolling diameter.
My Ford 1720 came with factory turf tires that were grossly miss-matched. On dirt & snow the fronts were trying to walk away from the rears. If I be was to coast mmgoing straight in 4wd it would come to a whining stop within 10 feet.
I resolved this by slowly reducing the air pressure in the front tires until I could drive on blacktop in 4wd with no binding.
Next I marked the front tire’s where they contacted the floor and rolled it exactly 1 turn. I then measured the distance between marks and used Tire Rack’s website to find an auto tire with the correct diameter. I bought 2 radial snows after determining what I needed then fine tuned the f&r pressures until I could run down the road in 4wd with no binding.

Didn’t intend to turn this thread in another direction but I felt it was a good opportunity to bring awareness to tire size and how to identify a miss match & calculate a solution.
90cummins

One major issue is that all the manufactures make a tire labeled with the same dimensions that have a different loaded radius, or rolling circumference. And then every load will change the loaded radius, with all loads being different the tires will never be in perfect sync all the time.
Some lead is also desired for most operation.

 

[LD1]

One major issue is that all the manufactures make a tire labeled with the same dimensions that have a different loaded radius, or rolling circumference. And then every load will change the loaded radius, with all loads being different the tires will never be in perfect sync all the time.
Some lead is also desired for most operation.

A little lead is also desirable when turning since the front makes a wider arc.

That's why pickups bind when turning with equal size tires and ratios