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14.9 Tires on 28 x 13 Rims

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Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=186914
Printed Date: 24 Jul 2025 at 1:53pm
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Topic: 14.9 Tires on 28 x 13 Rims
Posted By: Gatz in NE
Subject: 14.9 Tires on 28 x 13 Rims
Date Posted: 09 Mar 2022 at 12:19pm
Does anyone know the dimensions for the CIRCUMFERENCE (or diameter) and WIDTH of 14.9 tires mounted on 28 x 13" rims ?

TIA
gatz



Replies:
Posted By: DrAllis
Date Posted: 09 Mar 2022 at 12:29pm

The "rolling radius" or half the diameter is listed n my D-17 IV book at home. The actual number will depend on what brand of tire it is. I've got a set of BKT brand on my WD45 on 13 inch rims (from a D-17) and they stand up just almost the same height as a friends newer 16.9 x 28 Firestones. Disappointing the F.S. have been cheapened up that much.



Posted By: Ed (Ont)
Date Posted: 09 Mar 2022 at 3:59pm
I have 14.9 x 28 Firestone on 13" rims. Can try to do some measuring if you really need it. But they sure look good. They are older ones. I've had them for 10 or more years and they were old stock when I bought them so it was a pretty good deal. My rims were in bad shape so I bought new 13" rims at the same time.


Posted By: Joe(TX)
Date Posted: 09 Mar 2022 at 5:31pm
14.9 overall width, 26.3 loaded rolling radius, 53.8 overall dia.
Google tire data book ag tractor


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1970 190XT, 1973 200, 1962 D-19 Diesel, 1979 7010, 1957 WD45, 1950 WD, 1961 D17, Speed Patrol, D14, All crop 66 big bin, 180 diesel, 1970 170 diesel, FP80 forklift. Gleaner A


Posted By: DrAllis
Date Posted: 09 Mar 2022 at 5:49pm
My Firestone "Traction Field & Road" chart (it's an old chart) says 53.5 inches diameter and 24.5 inches static loaded radius.  So, for circumference 53.5 x 3.14 equals 168 inches circumference ?  Right ??


Posted By: Gatz in NE
Date Posted: 09 Mar 2022 at 9:43pm
Thanks for the info, guys

Firestone "Super All-Traction II 23ยบ" fits the specs that Joe & Doc have posted,
except that they give the rolling circumference as 159".
Close enough for what I'm doing.


Posted By: DaveKamp
Date Posted: 10 Mar 2022 at 7:14am
Most of the time, when guys ask these kinds of questions, it's for one of three reasons:

1) They have some other brand of tire, and they're trying to find a replacement that will 'match' without being lop-sided...

2) They're working with an application that either has, or WILL have other driven axles (i.e. FWD/FWA) and are trying to match driveline proportions.

3) They're concerned about wether it 'looks right' in a fender.

A tire, when mounted on a rim, will assume a shape based on the tire's design profile, but heavily affected by the rim width, and as a result, the standing height of the tire, and it's free circumference, will change slightly.

The tire, when installed, will exhibit a curious flat-spot on the bottom, where it contacts the ground.  This flat spot will do several things... first, it affects the distance from the center of the hub, to the ground... i.e. the 'loaded radius'.  As a result of that flat spot, the forward travel that the tire makes in one rotation, is not exactly the same as the distance it would travel if it was exactly the same as if it was perfectly round.

This is why, when you do a measurement of an automotive tire, then look up it's design dimensions and rated Revolutions Per Mile, they don't match up-  it's because the manufacturer has calculated in the actual running radius when loaded, and at the proper temperature.

One can minimize the variation, aka the 'size of the flat spot', by increasing tire pressure.  On a very hard surface, this reduces the surface contact area, but causes the area in contact to be subjected to extreme loading... lots of heat, and accellerated wear.

One of the cool things about tire design, is that when rolling, the actual area in contact with the ground is an entirely DIFFERENT shape, from what that same tire area is when NOT in contact... and it  is because of this change-of-shape, that a tread that has become plugged with mud, readily sheds that mud...  Escoteric information, but necessary for understanding real life operation.

IF you're asking because of driveline considerations, then the most important point prevails-  an all-wheel drive circumstance ALWAYS results in a disparity between wheels... there's a right-to-left disparity due to change in rolling distance in a turn, and there's a front-to-rear disparity as a result of Ackerman Angle (front wheels travelling farther than rear).  The exception here, is that MANY articulating tractors have symmetrical front/rear pivot distance geometry, and as a result, the theoretical travel of front and rear axles SHOULD be the same...

But in the end, you have some wheels that need to roll farther than others, and when there's a load on the drawbar, or a hill to climb, the driveline binds up a little bit, and eventually there's enough force against soil that Mother Nature finds some way to resolve the dispute.

If you're worried about how it looks, there isn't enough mud on your tractor yet... LOL


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Ten Amendments, Ten Commandments, and one Golden Rule solve most every problem. Citrus hand-cleaner with Pumice does the rest.


Posted By: Dave (NE)
Date Posted: 10 Mar 2022 at 7:33am
What are you up to Gatz?  Get another tractor?

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Do not argue with an idiot. He will drag you down to his level and beat you with experience. Mark Twain.


Posted By: Gatz in NE
Date Posted: 10 Mar 2022 at 9:39am
DaveK, thanks for the info. ...... much appreciated.

Dave W, Just knockin' around some ideas.
gatz



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