Gear Ratios

[fjxt3]

I'm still struggling with tire sizes for the 1510D. Does anyone know the actual gear ratios (final drive ratios) in the front and rear differentials of the 1510D? I've read through the discussions and I've read through the manuals that came with the tractor and I can't come up with the numbers.

 

[turnerbend]

Please enlighten me on why the gear ratios is so important when buying tires??

 

[dieselfuelonly]

Well, since his tractor is 4WD, I'm guessing it may be important because when in 4WD, the tractors are geared so that the smaller front tires turn faster than the larger rear tires so that both sets of tires (front and rear) pull along at the same speed, since the front tires would have to turn more times to keep up with the larger rear tires, right?

Sorry I can't be of much help, maybe ask Hoye Tractor?

 

[oliver28472]

Gear ratios and tire sizes come into play when the 4WD is engaged. Tires have to be sized properly so that when 4WD is engaged, the front and back tires pull at close to the same rate. Otherwise there would be more wear/binding on the gears. This really becomes obvious when you have your tractor in 4WD and make a sharp turn on dry pavement. The front tires travel a longer distance in a turn than the back tires.

 

[Mickey_Fx]

I'm sure I read somewhere the front tires actually turn a little faster (ground speed) than the rears.

 

[blackd]

IIRC, the difference should be within +-3% front to back. They almost never match up perfectly due to wear and replacement schedules.

 

[dieselfuelonly]

Yeah, when I say the same speed, I mean "close" to the same speed.

Sorry if I confused someone.

 

[fjxt3]

It's true. Everything that is said about 4WD and tire sizes, etc. Some in the industry have used 0% to 5% positive slip, some have used + or - 5%, some have used 3%. Regardless of which number you use, the actual final ratios are part of the slippage calculation. I have found a number of ways to estimate the ratios in the discussion groups along with a lot of discussion on the topic in general but I have yet to figure out what the real ratios are and I haven't yet been able to find anyone who knows. I really appreciate the responses and I'll post the answer if I find it.

 

[turnerbend]

Could you just put the manufacturer original spec sizes tires back on?

 

[fjxt3]

Came with "rice tires" 8-18 on the rear, 5-12 on the front. I want to replace them with something a little friendlier. Put 275/70R18 truck tires on the rear and 5.30-12 on the front. Seems OK as far as the ratios go. The 5.30-12 tires are still pretty narrow. I would like a bit more flotation. 8-18 and 5-12 ag tires are not an option. I think I will likely look for wider wheels. I had hoped to find tires without replacing the wheels. Local Les Schwab store can have wheels made but then the gear ratio becomes even more important.