1997 - 2003 F-150

37's/38's on a 4.2 HELP/SUGGESTIONS

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Old Jul 4, 2012 | 07:39 PM
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37's/38's on a 4.2 HELP/SUGGESTIONS

OK....97 4.2 4x4 f150 219,000

right now ive got 5 inch rcx with 295/75/16 on 16x10 wheels....
i just got a 98 f150 8.8 axle on craigslist with 4.88s in it that im gonna put in my truck....so i want bigger tires...right now i can easily fit 315's...but i was thinking going bigger because of such a lower gear ill have...only concern is if that little 4.2 v6 has the ***** for such a big tire....i really want a 37 13.50...but im wondering if i should just stick with a 315 because of my baby engine....please, suggestions, ideas, comments...
 
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Old Jul 4, 2012 | 10:13 PM
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I think the 4.88s would be a good match to the 35s because of the 4.2 but I don't think it would be bad on 37s either though.
 
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Old Jul 5, 2012 | 08:10 AM
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Yeah I'm scared I'm just gonna kill my truck. . Like rev it to high with 4.88s and 35s or just wear it out with 38s . . (All I can really find is a 38 15.50)
 
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Old Jul 5, 2012 | 11:07 AM
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Are you planning on adding a body lift too man?
 
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Old Jul 5, 2012 | 11:49 AM
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toyo open countrys come in a 38x13.50
 
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Old Jul 5, 2012 | 12:02 PM
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That engine will be fine since you are going with the 4.88 gears. And I don't know what you plan on using the truck for, but if it is your daily driver I would go with the toyo M/T's. Good looking tire, aggressive enough for mud, and does great on the highway. Smooth, quiet, and long lasting for a mud tire.
 
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Old Jul 5, 2012 | 12:38 PM
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Yeah I would do a bl if I did 38s . . . I have a commuter dd truck so I can play with my f150 . . I just don't wanna kill it. . It's got a lotta miles. . . I just wonder if the 35s and 4.88s would rev too high doin like 75
 
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Old Jul 5, 2012 | 01:14 PM
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Do you have an automatic or manual transmission?

With 4.88's and 35's at 75 mph, an automatic in OD with the TC locked will be turning 2460 rpm, with a manual in 5th it will be turning 2811 rpm. Considering the engine redline is over 5000 rpm, you won't have any problem but the gas mileage is going to suck.
 
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Old Jul 5, 2012 | 01:27 PM
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Thanks glc. . I have automatic. . So theoretically would my mpgs be better with 38s?
 
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Old Jul 5, 2012 | 02:35 PM
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Nope. With 35's or larger, no matter which axle ratio you have, the mileage will suck, especially with a lift. Doesn't matter which engine you have.
 
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Old Jul 5, 2012 | 03:12 PM
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Don't enter any 'tug O war' pulling contests!

That stock IFS is the next weak link as will the 8.8 rear, even with the V6... You'll be sending a lot of torque to those axles thru the auto and those low gears..

Good luck and have fun with it!

Mitch
 
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Old Jul 5, 2012 | 03:28 PM
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i ran 46's with my 4.2l no engine problems. Gearing is everything
 
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Old Jul 6, 2012 | 12:05 AM
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Yeah I know mileage will suck. . I hope it does improve in town though. . I think I might just go with a 35 . . I was just at my buddies house and his bro has 4 new 36 13.50s sittin in the garage . . Things are freakin huge . . I can't imagine a 37 or 38 on my truck
 
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Old Jul 6, 2012 | 12:55 AM
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Just don't forget you need to change your front gearing as well.
 
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Old Jul 6, 2012 | 05:32 PM
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Yeah I know. . I'm just gonna not put it in 4wheel until I do
 
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