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Tire Sizes and Gas Mileage

Discussion in 'The Garage' started by spac30dyss3y, Jan 3, 2003.

  1. spac30dyss3y

    spac30dyss3y Registered Member

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    How does different tread designs affect gas mileage (ie Mud terrain vs. All Terrain)? Is there a significant decrease in gas mileage with an MT vs an AT? How would size affect Mileage as well? I Have 31 AT's now and am thinking about switching to 32-33 MT's? Would there be a significant decrease in gas mileage? And if any, how much(1MPG or what...)? I am probably going to be driving on the freeway more than off-road, but i still want to have something that's good in the mud and terrain in general. I don't have the cash to buy two sets of tires so thats not feasible. I may start a war but any suggestions on a good overall tire for both mud, and rocks, but also drives smoothly on the freeway and is easy to control. I have to drive about 30 minutes each day to school one way, most of it being on the highway, but occasionally after school my friends and i go out and play in some ditches in the country, so i need something that won't get me stuck. Sorry, if this has been asked before. Thanks for any replies.

    P.S. What are the Pro/Con's of Manual Locking hubs vs Auto Locking Hubs?

    Thanks again for any replies...
     
  2. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    Tire size affects gearing of the vehicle. Going to a larger tire will raise the gear ratio while going to a smaller tire will will lower the gear ration. A good place to look at is 4lo. They have several calculators and there is one that will give you different RPMs with different tire sizes and gear ratios and also tells you what the optimum gear ratio is.

    One thing that would help is to know what you are driving. If you have an overdrive transmission, you can get away with a slightly lower gear ratio. More than likely though, your truck has been geared to match the 31" tires that you have now. 3.73 gears with 33" is on the edge of being geared too high. More information on that would help.

    As for tread designs affecting mileage, I can't really answer. But for what tire that would be suffecient for you. Are you in snow country? This would affect your choice somewhat. But with what you have given, I can only give you one tire recommendation and that would bea BF Goodrich Mud Terrain. Yes, they are a little more $$$$$, but worth it. They get great traction off road, the on road mannerisms is nice with no outstanding road noise and can withstand off road punishment. From what you described, you basically are in the same boat as I am when it comes to vehicle use. The tires also wear great, I have approximately 60,000 miles on my set and been running them for 5.5 years. They are a little past due for replacement and I'm getting ready to put on new tires.

    Hope this helps.
     
  3. spac30dyss3y

    spac30dyss3y Registered Member

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    Thanks for replying.

    Yeah, My trucks got an OD Automatic Tranny. As for gearing, I don't know. How hard do your tires ride? I'm thinking about Interco Thornbirds, has anyone heard anything bad about these tires? The BFG MT's look good as well.
     
  4. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    You might want to give us more details like filling out your profile just a little.

    Thornbirds, I drove a Toyota one time with them, rode like crap. Other than that, I know nothing of them. The BFG tires are composed of a harder rubber compound than some other tires, that's why they last so long. As for how hard they ride, it all depends what I have my air pressure up to. I usually keep it at 35 psi, so it doesn't help ride quality, but a person can get away with running a little lower and softening them up a little. I'm totally happy with them and unless a company decides to dump tires in my lap for free, I'm not changing.
     
  5. spac30dyss3y

    spac30dyss3y Registered Member

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    What about Pro Comp tires?
     
  6. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    All I know is that I wouldn't have them. I know nothing of them. Sorry.
     
  7. spac30dyss3y

    spac30dyss3y Registered Member

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    Thanks for your time... My vehicle is an 86 ford bronco, (not my choice), I came across this website while looking to buy an 85-86 Blazer, and figured "wheeling" is "wheeling" no matter what kinda vehicle you got, so I thought I would get my questions answered here. The Bronco was a choice between Me paying for a Blazer, and my dad paying for the Bronco? Decisions, Decisions, eh? Both my Dad and I are chevy people, so the Ford is just a waypoint till i have money to buy a Blazer in good condition, plus it was really cheap. Okay that's my story... Thanks again for answering my questions.
     
  8. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    Central Valley huh? Where at exactly? There's a lot of us around here. Don't know if you are interested, but we have a club that encompasses Northern Cali, we have a forum down the page, check us out. Even though it's mostly Chevy's, all makes are welcome. As for the Bronco thing, that's no biggy. They got some good points.
     
  9. spac30dyss3y

    spac30dyss3y Registered Member

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    Visalia actually. I'm a big chevy guy, so it's kinda sad to have a Ford, but it's a first vehicle so it's cool. I live in Visalia, if that means anything, you?
     
  10. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    Really huh, I'm out here on the west side of town. /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif
     
  11. Pookster

    Pookster 1/2 ton status

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    I went wheeling in NC with a bunch of guys.. nobody had the same tires.. I have the uniroyal lareado's MT, they are the same tread as the BFG MT's . dunno if its the same compound. But I can tell you this, I made it through every everything on those. They are noisier than 31" AT's, but thats to be expected. I've heard that the BFG's are a bit quieter. Gearing wise, if your motor is still strong, i drove around a year with 33" on, over several thousand miles. Wasnt a problem with gearing. but I drive gentle. I dont like to break things. /forums/images/graemlins/smile.gif
     
  12. K05Aggie

    K05Aggie 1/2 ton status

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    I do not think you will see a measurable difference in mileage. As was mentioned earlier the gearing will change, lowering engine RPM which inproves efficiency(since all of the parts are moving slower, there is less friction). However, the larger tires will raise your vehicle 1/2 or 3/4 of an inch increasing the amount of air flowing (and turbulence) under your Bronco which will increase drag. Also, there is 1/2 or 3/4 of an inch more tire being pushed through the air, again, increasing drag. If the tires are wider, this will have more of an effect than the height difference. I don't think tread pattern will have any effect. I'm not an expert so take from this what you will.

    As for the hubs, I think manual hubs are stronger. I still have automatic hubs and they have never failed me. I know there have been a few posts on which are better or which manual hubs are the best.
     
  13. st08x

    st08x Registered Member

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    hey a note on the thornbirds, i had them for a week and decided the road noise was too bad, but as for off road the were very good
     
  14. Highjaxx

    Highjaxx 1/2 ton status

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    I heard the thornbirds seperate, suck in the mud, are terrible on rocks, and average on dirt. Did I mention they hydroplane like ski's. Get the SSR's or SX's. /forums/images/graemlins/thumb.gif
     
  15. new2k5

    new2k5 1/2 ton status

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    thornbirds should only be run on show trucks on the road they act like an unbalanced bald tire. they suck in the rain and snow and off road they pack with mud easier than a at there only good point is decent sidewalls.

    bfg mt'sare mediocre in my opinion i have had 3 sets on different vehichles off road they grip decent they have fairly strong sidewalls but atill provide no wet road traction

    ssr's are great offroad tough sidewalls and actually grip a wet road and if you keep your truck aligned and rotate tire at every oil change you can get 45K + out of em /forums/images/graemlins/thumb.gif

    swamper truxus MT is going to be my next tire from what interco says about em they should be the best all around tire money can buy at a decent price to boot /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif
     
  16. spac30dyss3y

    spac30dyss3y Registered Member

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    It turns out that I'm not getting the Bronco, we were still in the purchasing stage, and it had too many issues to be worthwhile buying. So now, I'm in the market for buying a mid 80's blazer!!!!!! /forums/images/graemlins/ooo.gif How does a bigger tire affect low range torque? I know torque is important to Wheelin' so my thought is that because you are having to push more rubber to accelerate down the road (or move around period) that this would affect low-end torque, is that so?
     
  17. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    A taller tire size affects the gearing. It will raise the gear ratio and that will lower the torque.

    I would ask you which Bronco you were looking at, but I never get around town anymore since I work up in Fresno.
     
  18. spac30dyss3y

    spac30dyss3y Registered Member

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    I was looking at a bronco on the north east side of town off Ben Maddox, hidden away a bit. It was in pretty bad shape, needed a new tranny and had other issues. It's too late now to change my mind. If I change the gears in the diffs, will that reset the torque, or is that what you are talking about (re-gearing).
     
  19. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    </font><blockquote><font class="small">In reply to:</font><hr />
    It's too late now to change my mind. If I change the gears in the diffs, will that reset the torque, or is that what you are talking about (re-gearing).


    [/ QUOTE ]
    Yep. There's a chart over at 4lo.com that shows RPM for a given tire and gear combination. The "choice" gearing is shaded in different colors. For example, I currently run 3.73 gears with 33" tires. I run a little lower RPM and I do get into trouble on big hills, but it's a good all around gear. When I move up to 35" tires, to keep goo torque, I will have to regear to 4.11 gears, or since I have a 700R4 tranny, I can step up to 4.56 gears.
     
  20. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    </font><blockquote><font class="small">In reply to:</font><hr />
    I was looking at a bronco on the north east side of town off Ben Maddox, hidden away a bit.

    [/ QUOTE ]
    I tend to stay away from there unless I go to Napa. I've only been up there twice in the last year or so. Don't like getting shot at. /forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif
     

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