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Help! I'm overthinking tire sizes!

blubuckaroo

Grease Monkey
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Jun 11, 2007
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Ridgefield WA
If you're trying to decide between 31", 33", 35"... you also need to consider your axles, gear ratio, and brakes. Gear ratios are easy, but brakes are taxed by taller tire diameter. Also, the traditional limit for 28 spline axles is 33" tires.
 
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NickMcAFP

NickMcAFP

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Sturbridge
If you're trying to decide between 31", 33", 35"... you also need to consider your axles, gear ratio, and brakes. Gear ratios are easy, but brakes are taxed by taller tire diameter. Also, the traditional limit for 28 spline axles is 33" tires.
I'm mostly trying to decide between 31, 32, and 33s. Probably more 32s and 33s at this point. With either 32s or 33s I'd be putting in 4.11s. Power brakes are in discussion as well as power steering.

You're running 33x10.50s aren't you?
 

DirtDonk

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Bronco Guru
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43,179
Sounds like you like the 15" wheels, but if you can find a 16 you like you could go with a 265/75-16 tire. Gets you what amounts to a narrow 33. Somewhat of a 33x11.50-ish size in actual numbers. Would fit a 7 or 8 inch wide wheel too.
Only trouble with larger diameters is finding lower load range tires. A C range is better than an E range any day of the week for a Bronco type vehicle. The E-range tires are made for heavier trucks that need stout tires to carry heavy overloads.

There are some 33's with narrow cross sections, but not sure of a real 33x11.50 out there other than the Super Swamper Thornbirds. Which for a street rig you do NOT want because of their horrible road manners compared to most other tires. They look great, but are super loud and super squirrely.
Might be some Mickey Thompsons in the sizes discussed here. They have a lot of new interesting looking tread designs in the last couple of years, and lots of interesting sizes.

Paul
 

gnpenning

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I have more questions than answers.
I will differ on one thing, gears. My 74 with a C4 and stock motor wasn't very impressive. I went to a 32" BFG AT (love the tire) and it was even worse. Regeared but went to the 4:30 gears, night and day difference. I'm not interested in going real fast on the road, 65 is plenty fast for me in a lifted short wheel base vehicle. I wanted more of a dirt vehicle that may get driven around town.
 

sprdv1

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I'm in a mental death spiral over tire sizing. Over the past year I've really come to terms with what I want vs what I need out of my build and it is causing me to question the automatic tire choice I made at the beginning of this journey.

Quick overview: My father passed a year ago and left me his 1975 bronco. It needed EVERYTHING so I sent it to a friend I trust to be completely rebuilt. I haven't had the luxury of being able to experience it and upgrade it over time. I just have to make up my mind and hope I'm right.

On day one I decided on 33s with the words of my father still echoing in my head that that is the perfect size tire for an Early Bronco. He had been telling me this since I was like 6 years old. He also really enjoyed offroading so there was a practical reason for the 33s. I DO really like the way they look.

The issue: I want this to be a daily driver (more or less). I can't help but wonder if I would enjoy actually driving it more with more road friendly tires. 31X10.50s look good. They aren't as exciting but they look fine. 32s also look fine..

I have another car at my disposal all the time so I never HAVE to drive the Bronco but why the heck wouldn't I drive it if I had the option???

The quarters are the Dennis Carpenter quarters and there's going to be a 2.5 inch suspension lift. Mostly stock, cleaned up, factory 302. Factory carb. Wide ratio 4 Speed top loader. I'd be gearing the axles to suit whatever tires I land on.

Thank you in advance! This is actually keeping me up at night.

well stop that LOL you'll get the best views here and experience
 

sprdv1

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The 12.50's almost always stick out some. But fender flares minimize that.
However the key to how much or how little they stick out past the sheet metal and flares is the wheel the tire is mounted to. After all, a 12.50 is a 12.50, whether it's a 33 or 35 or even 37.

The wheel width and backspacing/offset are key to looks, sometimes road manners, and definitely fitment. Put a tire on an 8" wheel with 5" of backspacing and it's tucked in pretty decently. Put that same exact tire on a 10" wheel with 3" of backspacing, and it sticks out like a skateboard!

Depends on what you like for look / stance
 

sprdv1

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I wasn't planning on running flares. I was looking at those 15 inch Indy mags. I think the backspacing on the 15x8s is 4. I have an unknown disk brake setup in the front though so I'm not sure how they'll fit without spacers

Definitely something to think about
 

sprdv1

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Oh, the other thing about wheel fitment and backspacing would be if the disc conversion was using '76 or '77 Bronco disc brakes. That's where the more traditional issue comes up. Not of the wheel hitting the brake caliper or backing plate, but of the wheel edge hitting the actual tie-rod ends where they mount to the steering arms.
That's where backspacing is an issue once it gets over 3 5/8" or so. Until you get into a 17" wheel, where that issue almost goes away completely.

Spacing is key for sure.
 

sprdv1

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With stock uncut fenders you always have to look out for rubbing. Are you cut in the back? Or was that you that said you've got the new DC rear fenders? I thought it was someone else today, but I could have everyone mixed up.
If you have stock uncut fenders in the rear, then the discussion of 33's (of any width) and 285's takes on a whole new level of discussion.

oh and that's true too.. sorry i forgot to finish my thought too

We'll keep up w/what you decide on here..
 

sprdv1

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Yes I have, but have always been a BFG/Michelin guy, but as of late they have not had the quality control that they used to, been very disappointed. getting round ones is difficult and belts moving has been horrible. My f350 had 3 tires that would not balance at 25k. But in the past I would get 65k out of KO2 and KO3's. I've just become a fan of buy a name that you recognize, that isn't the new name on the corner and if made in the USA even better.

I

Lot of new brands these days, that are just as good. Just got to do the research
 
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