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Which Tire?

  • 32x11.5x15

    Votes: 6 25.0%
  • 33x10.5x15

    Votes: 4 16.7%
  • 33x11.5x15 (if I can find them)

    Votes: 2 8.3%
  • 33x12.5x15 (if I can find someone to mount them & if its ok to take them on a long trip)

    Votes: 12 50.0%
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Discussion Starter · #1 ·
Ok I have an 89 bronco that has stock suspension and rims. I need new tires and I am debating on what I want to put on it, right now I have 31x10.5x15. The usage of this will be about %60 on and %40 off road. I pretty sure I want to go with BFG T/A KOs because they seem like a good all around tire. Now I am not sure what size I want to go with. I really don’t have any plans for a lift or changing out rims right now. Also in the not to distant future I will need to drive the bronco 1700 mi. With that being said I want some better grip for off roading, a little bit higher ride height with bigger tires, and a little meatier look. If I go with 33s I will test for rubbing areas before I purchase. What are your thoughts? I am thinking I really want 33s but don’t know if they are the best chose. Also sorry if this seems like a lot of other threads but I have searched through the forums, now I just want your guys’ opinion. Thanks

PS I have heard of 33x11.5x15 but a few places I have checked don't carry them. Also Discount Tire Company said they would not mount 33x12.5 on my rim and with my needing to travel long distance with it, are these tires out of question?
 

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Bronco Master
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599 Posts
Your stock wheels will work for any of the tire sizes listed. I ran my Bronco for a year with 32x11.5 on 8" wide wheels (4" backspace) when it was stock. The size worked well. Next I went to the 33x12.5 on the same 8" wide wheels. They worked well and fit fine stock. 10" wide wheels cause tires to rub. Each time I went bigger the fuel economy went lower. I think the 33x10.5 might be an ideal size. The extra width of the 12.5 definately doesn't help the mileage, and the 10.5 would clear the radius arms for tighter steering. BFG's always worked well for me in everything except deep mud.

I'm shopping for tires for my diesel right now. The stock tires are a 265/70/17 (31.4x10.5). I'm looking for something in a 33x10.5R17 with an E load rating. The closest things I'm finding are a 285/70/17 (32.8x11.5) or a 275/70/18 (33.1x11). Taller tires will give it better gearing for going 80 mph on the freeway, but I don't want to go wider because it will mean more rolling resistance, or lower fuel economy.
 

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Discussion Starter · #4 ·
I just found out that my rims are 8in. I need to look into trimming to maybe fit 33x12.5. How much gas milage loss is knoticed? Also would I need to look into back spacing with my 8in rims?
 

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Bronco Master
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599 Posts
Your factory rims are 4" backspacing, so they are fine. Some tire shops have an issue mounting a 12.5" wide tire on the 10 hole aluminum wheels because they are 7.5" wide.

I couldn't quantify the exact amount of gas mileage lost. The best my bronco ever did stock with 32" tires was 16 mpg. After going to 33" tires and later a 3" lift it dropped to 14 mpg or so. With 35" tires, 4.10 gears, and a 4" lift it was getting 13 mpg. Currently with a modified suspension, 35" aggressive tires, and 4.10 gears it is getting about 11.5 mpg on the highway. Since I seldomly drive it, I really doesn't matter what kind of mileage it gets.

If the tires are too tall the truck will fall out of it's power band on the highway, making the engine work harder. The wider the tire the more rolling resistance makes them harder to turn. Both of these factors make it use more fuel.
 
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