off color(almost) 4X4 tire question...
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Forum Name: Farm Equipment
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=145095
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Topic: off color(almost) 4X4 tire question...
Posted By: DiyDave
Subject: off color(almost) 4X4 tire question...
Date Posted: 04 Dec 2017 at 7:42pm
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Gots a Kubota 4x4 tractor that I wanna put new skins on. Original turf tires are 33 12.50 X 15, on the rear(33.8" rolling dia), 23 850 X12, on the front( 23.2" rolling dia). Hadda craigs list find hit me today, found same size fronts + 16" rear rims, fer $100, bout an hour from home, so I grabbed 'em. Here comes the questions. Found 9.5X16 R1's are 33.6 rolling diameter, at least on m.e miller's page... from the same source, 23 8.50X12's, in R4's (only ones I can find in the size) are 22.6" rolling dia. If I do the math that comes out to 1.45689 f-r ratio for original, and 1.48672 f-r for the new tires. question is, is what is the allowed variance in tire sizes, expressed as a percentage? Is there a general formula, for this? My gut says that .02983 won't make much slippage, except maybe on pavement, and since the gut's bigger than the brain, that's the way I would tend to go with this, unless somebody else has a better ideer
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Replies:
Posted By: Tbone95
Date Posted: 05 Dec 2017 at 8:20am
| Interesting! You can turn off the 4wd when not needed, right? And when you need it, you're already slipping........seems it would be fine, but I only have the gut too. |
Posted By: Ray54
Date Posted: 05 Dec 2017 at 3:38pm
| I have a White 60,Fiat build 60+ hp that has MFWD. Could not find any 16.9X30 used but did find 18.4 X 30. I still worry a bit about this but it never gives any indication that of binding or bucking. I went out on the pavement and put it in 4x4 just to see how it reacted. So I try to save the 4x4 for when I really need it. Not real proof that it will not destroy things as it only has maybe 500 hour since and except for the test only used 4x4 where there is a lot of slip. |
Posted By: DaveKamp
Date Posted: 05 Dec 2017 at 11:52pm
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Such a small change in ratio will have no discernable impact on operation. You'll see much more variation simply as a result of changing tire SHAPE due to temperature. In any case, if you're in 4wd, it's because you're on a marginal surface anyway, so that slip number is irrelevant. If you were to have a perfect match, and decided to steer to the left or the right, you'd be binding the driveline front-to-rear, simply because the front tires NEED to turn a greater radius than the rears. When you attempt to make a tight turn on dry pavement, the machine refuses to comply for the simple reason that front wheels have to turn that greater radius.. if your machine doesn't have a center diffierential... it's gonna bind. Don't drive in 4wd on good surfaces! ------------- Ten Amendments, Ten Commandments, and one Golden Rule solve most every problem. Citrus hand-cleaner with Pumice does the rest. |
Posted By: wekracer
Date Posted: 06 Dec 2017 at 3:22pm
| They are designed for the front end to run 6% faster than the rear. A good friend worked for Case he said anything over 10% would power hop and closer to 0 would steer poorly as Dave said. Just don’t lock it in unless you are having wheel slippage or you know your going into a sticky spot. |