Correct Tire Sizes

[Mark Page]

Last December Massey was having a promotion that could not be passed up. With any 2600 series tractor they were throwing in a free loader and a discount for cash. The deal ended 12/31 and I found out about it around the 20th. I had little time to make a decision and pull the trigger. The only catch was that the only 2615 available had R4s on it, 24 inch rear tires with 18 inch fronts, instead of 28 inch rears and 18 inch fronts. This was almost a deal breaker as I've always had 28 inch rears. I could see no advantage to 24's. Rougher ride, poorer traction maybe more power to the ground. The deal was 2 sweet and I bought it. We had no snow last year so I had no chance to check out the 4wd on a slippery surface. The only reason I bought the tractor was I wanted 4wd for dealing with snow.
Now I'm concerned about this difference in tire size. Are 18 inch fronts going to work with 24 inch rears when the tractor, as advertised, comes with 28 inch rears. Was a gear ratio in the trans switched out to work with the 24s. Was this tractor ordered this way for some reason and then the deal fell through? I've mowed a bit with it in 4wd and it seems fine, but grass and black top are 2 different ?things. It's been suggested I try running it in 4wd on dry pavement, which sounds like a good idea. If I make a hard turn in 4wd on grass shouldn't it buck like my pickups and SUVs have always done.
The dealer keeps telling me that it will be fine but without a clear explanation as to why.
Am I worying about nothing?

 

[Zebrafive]

Mark you posted a link last month on how to check front tire lead/lag. Have you tried doing this?

I don't know if Massey has parts online like John Deere does, but for my 6415 mfwd, JD lists multiple gear pairs, 20+ for the front drive of the transmission. That would be a place to check if Massey has parts online.

My guess is the ratio was determined for the tires ordered when the tractor was built.

I would not drive on pavement to check.

 

[MHarryE]

I first thought there may not be much difference in rolling circumference between the 2 tires. I took a guess at tire sizes. You Massey is listed with the standard tire size being 13.6 x 28 R-1 rears with 157 inch rolling circumference. I took a guess that it is equipped with 17.5L x 24 rears which have a 145 inch rolling circumference. That is an 8% difference which would be considered significant. However I don't know what the front tire sizes are. My Kubota, for example, would pair a 9.5 x 16 front with a 13.6 x 28 rear for R-1 tires, and a 10.5 x 16.5 front with a 17.5L x 24 rear for R-4 tires. If your tractor has that combination R-4 tires, your tractor should be set up correctly. I used the Titan on line information because my tractor is equipped with Titans but I have found the information on line from all major tire suppliers (remember Titan makes Goodyear ag tires so you find both Titan and Goodyear data under the Titan site). The important dimensions for you to look for are rolling circumference and static loaded radius.

 

[Mark Page]

I have 15.1/80- 18s up front and 14.9 24's in the rear. Not positive about the front widths.
It turns out that all 2615s with R4 rires come with 24 inch rear rims. Order R1s and you get 28s.
I don't understand why they would go with 24 inch rears when, IMHO, 28s would be so much better.
Thanks for your interest.
Mark

 

[Mark Page]

I have 15.1/80- 18s up front and 14.9 24's in the rear. Not positive about the front widths.
It turns out that all 2615s with R4 rires come with 24 inch rear rims. Order R1s and you get 28s.
I don't understand why they would go with 24 inch rears when, IMHO, 28s would be so much better.
Thanks for your interest.
Mark