I have a 1978 f-150 4x4 short bed, with a 300ci. I-6, manual trans., np205 transfer case, and a Dana 44 front and Ford 9" rear with 3.55 gears. At this time i have 33x12.50x15's on off set rims, and i want to put in a Detroit Locker ( or some type of limited slip) in the rear (with a mini spool up front) soon. But my question is; What are the biggest size tires that this drive train can handle? I plan on getting 33x12.50x15 Super Swampers but i would like to possibly get some 35x12.50's or the Super Swamper 36x12.50's. Just keep in mind that its a 1/2 ton drive train with a 300ci. Oh and i should mention that i go 4 wheel'n about every 2 weeks (so its not like i all ways have it on the trails) also because i have school, i use the truck as a daily driver.

 

If you go bigger on the tires change to lower gears (front and rear) and the I-6 will not have any problems.

Bob

 

 

You have your lockers backwards. A spool in the front will put you in a ditch the first corner you take. If anything, a spool in the back and a locker up front would be much better, though a locker in back and a limited slip up front would be more streetable.

As for your actual question, I wouldn't go over 33's with 3.55's. I think 33's would be better with 3.73's myself, and 35's with 4.10. So if you are to switch, i'd go with 35's and 4.10, but your current 3.55's will work with 33's. Any larger and you'll give up a bit too much first gear acceleration.


-=Whittey=-

 

I have a 1981 flareside with a 300 6 and 35x12.50 15 and a 1984 Bronco automatic 4x4 front diff and my little six turns the 35's with the original gears in my truck??? Seems ok

 

what gears does it have? and do you do any hard 4wheeling and mudding?

 

I don't know about the performance, but I found this truck on ebay kind of interesting. 300 I6 and (I'm guessing) the M50D.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=1820461940

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[font color="green"]1995 F-150 Supercab XLT longbed 4x4 302 M5OD [/font]31x10.50's
[font color="green"]1986 F-150 4x4 300 I6 NP435 [/font]Warn hubs, DeeZee bed caps, '96 XLT bench seat, new paint job

 

I have a 84 bronco w/300cid & NP-435 & NP-208 and I am running 35x12.50x15 with a 6" lift and for now the stock gears 3.55 I will be going to 4.56's but I have no prob's off-road on road I have to keep my foot on the gas to stay at 65mph or more and I have to use 1st starting on hills. But it still kicks butt on rocks!

 

I have 35" swampers on my 1992 F-150 with the inline 6 and 3.09 gears. It is a dog on the road but does ok in the mud because of the huge amount of torque. I plan on switching to a 4.56 rear end when i upgrade to 39" tires.

-Jon