Tale of the tape.

Farmwithjunk · Apr 6, 2006

Need a "field measurement". I'm looking for a couple front tires/wheels to level a tractor that's had bigger-than-stock rear tires added. I need to raise the front a couple inches.

OK. We start with 6.00X16"'s that measure 28.1/4". Firestone data book says 7.5L X 15" is 30.5" tall. (7.50X16 WAAAAAAAAAY too tall) The same book says my 6.00X16"'s are 29.25. (and I know that isn't accurate)

Anyone have a tractor with 3-rib tires, 7.5LX15"s, and could throw a tape measure on 'em for me. (Tractor currently has 6"X16" rims. I have a set of 6-lug, 7"X15" rims. That's what FireStone says the 7.5LX15" needs) Just don't want to buy $140 worth of tires only to find they aren't any taller than what I have.

Billy_S · Apr 6, 2006

Tire data book specifications are manufacturer specific. Specs do vary, sometimes quite a lot, between different tire makers. In addition, the specifications in data books are with the tire inflated on the proper wheel. There is often a significant difference in mesauring an inflated tire versus an uninflated one.

Would a tire 29.25" suit your needs? If so, all you have to do is buy the Firestone that is specified that dimension in their data book.

You do understand that if you go with a tire like a 7.5L-15 you will also have to buy different wheels? Your tractor currently has 16 inch wheels whereas the 7.5L-15 would go on a 15 inch wheel.

Edited to say DUH! I see you already have 15 inch wheels.

daTeacha · Apr 6, 2006

My SIL and daughter just sent me an adobe file of the Goodyear Farm Tire handbook. I presume they got it from the web somewhere. It's well over 100 pages of useful stuff just like what you're looking for. Maybe you can google around a little and find it. It might have something that Firestone doesn't have in theirs.

As another thought, maybe you need a two rib instead of a tri-rib with the high center rib?? Another thought -- Titan makes the 6 or 7 x 15 R1s on the back of my Kubota. Don't know the height of them or how desperate you are. One of my 8Ns had truck rims on the front, complete with brake drums, to carry some 6 ply truck tires that were 15s. The old 6 plys were/are something like an 83 aspect ratio, way taller than newer style tires. I think modern design tires get no taller than 75 aspect ratio.

frank_f15 · Apr 6, 2006

Have you actually discussed this with the tire dealer ? or just info from the book?

LRH · Apr 6, 2006

The tires with the "L" such as 7.50L-15 versus 7.00 or 7.50- are different aspect ratio. I have always presumed the L stands for low profile as the "L" tires are much wider and require a much wder rim in most cases.

Farmwithjunk · Apr 6, 2006

I posed the question to 3 different tire dealers that deal heavily in AG tires. Only one could give me any usefull info. Others didn't even know what BRAND of ribbed tire they sold.

Listed sizes from Firestone and Titan vary from what we already know as fact. (Both wrong by over 1" on 6.00X16's) I WANT something close to 30". Would LIKE to have 1-2" wider than the 6.00. 7.5LX15 looks like the prime suspect.

My Massey has 14.9X28 rears. It came with13.6X28's. The 14.9"s are almost 4" taller than 13.6"'s. I'd like to raise the front some, but not a lot. 2" to 3" dia. tire size increase would do it.

KiotiJohn · Apr 6, 2006

If your tractor is 4WD, be very careful to have the fronts and rears at the proper ratio, otherwise, the lead / lag of the rears to front will be off. This can lead to early tire wear, and linkage wear to possible linkage damage.
Read this article from Firestone to help you decide what is correct.
Lead/lag
John

Bill_C · Apr 6, 2006

Note also that mounted tire diameters depend on the width of the rim. The published data will assume a certain rim width. Go to a wider rim, the tire will be "shorter". Go to a narrower rim, the tire will be taller.

Also, it's really easy to underestimate the diameter of a mounted tire, when measuring with a tape measure. From the ground to the top of the tire isn't the diameter measurement cited in the literature--the measurement should be taken parallel to the ground, using a set of calipers (or an improvised approach....) This is the tire's diameter. The loaded radius is found by measuring from the ground to the center of the tire. If you measure from the ground to the top of the tire, you are actually measuring one half the tire's diameter plus the tire's loaded radius.

Another factor is tire pressure, even a few psi can make a difference (especially when mounted on a rim that's wider or narrower than the rim used by the manufacturer).

Farmwithjunk · Apr 7, 2006

No such animal as a 150 Massey 4WD. Talking 3-RIB tires.

Farmwithjunk · Apr 7, 2006

My measurements are/were done with the tire and wheel laying flat on its side. Actual diameter.

In the case of the 6.00X16"'s, they're mounted on O.E.M. rims, 6" wide, and that's what all manufacturers suggest. I have a set of 15"X7" 6-lug wheels. That is what manufacturers suggest for (among other things) the 7.5LX15. I'd be comparing one tire (on correct rim, vs. another tire mounted on correct rim. Brands vary in size, but there's got to be a good "ballpark" # that'll tell me IF and by how much the 7.5L is bigger than the 6.00. If it's an inch or less, it's not worth the trouble.

Later model (year) Masseys came equipped with this tire/wheel combo. Can't find one to measure though.