Tire size? Ratio between rear and front wheels?

[zipperno]

Hi

My 6341 Super came from the factory with 11.2 x24 front wheels and 16.9 x 30 rear wheels. I do not know which type of tires it had new so I dont know the exact circumference for the factory fitted wheels. But lets say a 11.2x24 wheel have aprox. 3300mm circumference and 16.9x30 has 4400mm. This gives me a ratio between rear vs. front at 1.33

Do anyone know what the exact ratio for this tractor should be??

Im asking because I want to go up to 34 inch rear wheels and need to find out what size the front wheels should have.


//Tom

 

[Renze]

Usually you need 12.4r24 with 16.9r34 rears

 

[zipperno]

Yes Renze you Are correct. But there is science to this... If I know the ratio I can calculate how big front tires needs to be vs. rear tires.

Front tires should run longer(faster) than the rear by 1-5%. Recommended around 3%.

Does anyone know the difference inside the front/rear diffs from a factory fitted 6341with 34" vs. One with 30"?
If i remeber correctly ive seen in the partsmanual a one tooth difference? 21 vs. 22?

I need to look in the manual and see.

 

[zipperno]

Here is a Swedish article on the subject. Maybe you can understand some of the charts.

https://www.maskinisten.net/download/file.php?id=8925

 

[Renze]

indeed there is a tooth difference for different drive ratios. However, the original sales guide also has charts for the rolling circumference of different brands of tires. Not all 16.9R34 tires have the same rolling circumference.

If you want to do it right, check up the rolling circumference of the original tires, then calculate your ratio and then choose tire brands and types that meet this ratio...

I know, too much fuss... 4wd isnt meant to be used on hard surfaces anyways.

 

[zipperno]

So what you are saying is that I will be fine even though the ratio isn't perfect because 4wd should only be used on slippery surfaces?

I can see the logic in that

 

[biely036341]

I got my 6341 new off the dealer lot. I told him I would buy it if he took the 12.4x24 and 16.9x34 off of a 7341 he had and replaced the 11.2x24 and 16.9x30 that were on the 6341. He did and I bought it. I very happy with that choice.

 

[zipperno]

Hi. Thank you for your input!

Have you been using 4wd much?

According to my calculations going to that size of tires wouldnt be adviceable. You raise the rear tire size more than the fronts. According to my calculations you should have even bigger front tires. Recommended is 13.6x24. This is just my opinion, I could be wrong, have been before

Did a little digging in the partsmanual and this is what I found:
11.2x24 and 16.9x30 has 23 cogs gear wheel
12.4x24 and 16.9x34 has 22 cogs gear wheel

13.6x24 is the only front tire that matches 16.9x34 and 23 cogs gear Wheel.

These are the possible variants of tires with either 22 or 23 cogs gear wheel:


------------------9.5x24-------11.2x24---------12.4x24------13.6x24

16.9x30________22__________23___________23____________

18.4x30_________________________________22____________

16.9x34_________________________________22_________23

 

[Renze]

If you use radial 16.9r34 and bias ply 12.4r24 you most likely get the right ratio because of the difference in loaded radius.

If you use a front loader, the weight split is even so its ok to have front snd rear drive speed equal when driving a curve.

 

[zipperno]

Its a 40 km/h tractor so it already has radials all around.

I contacted zetor to try and find out the factory ratio so I could calculate the exact overrun on the front axle. But they only replied this:

"Gear ratio is fixed numbered teeth on the wheel in the cabinet front drive (23 or 22 teeth, both are possible).

Overrun front drive varies according usage of tires."

 

[Renze]

Indeed, because the variation in rolling circumference between different brands and models of tires is quite big.

 

[biely036341]

I use 4x4 often. I have the original factory Barum tires on it. No unusual tire wear, no problem going into or out of 4x4. My tractor is a 2003, the 12.4/24 & 16.9/34 were optional. Just make sure you have the air pressure correct. When I do heavy loader work I put 10 pound additional air in the front. If I forget to let it out after I am done, the tractor will let me know the next time I go into 4x4.

 

[zipperno]

I use 4x4 often. I have the original factory Barum tires on it. No unusual tire wear, no problem going into or out of 4x4. My tractor is a 2003, the 12.4/24 & 16.9/34 were optional. Just make sure you have the air pressure correct. When I do heavy loader work I put 10 pound additional air in the front. If I forget to let it out after I am done, the tractor will let me know the next time I go into 4x4.

According to the spec sheet you should change gear wheel to 22 cogs. You have 23 today.

But as long as it works why change