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Max. Tire Recommendation for TTB Bronco's???


Well-Known Member
I'm looking into getting a Bronco and I'm curious about the maximum tire size for the Dana 44 TTB front end and the Ford 9". I have never had a Bronco or TTB before so just looking for some guidance; I have seen pre-runner/desert-race Bronco's with 39's on them quite a few time though. . .

It seems in the non-desert off-road world 37" seems to be the maximum recommended tire for a non-TTB Dana 44; I don't recall ever seeing a limit placed on the Ford 9".

I know the Ford 9" can be built as strong as you want and there are a LOT of options for beefing up the TTB front end as well so let's go with two scenarios:

First scenario, stock everything; second scenario, let's say cut & extended TTB with reinforcement plates, quality aftermarket gears, axles, etc. and a Ford 9" with 35 spline axles, quality gears, and top/back braces.

So you know why I'm asking. . .the plan is this Bronco will be donating it's chassis & drivetrain to body swap a vintage 4x4 (the wheelbases match, Bronco's are readily available at the right price, there are TONS of parts for them, and they seem to stay on the road for a LONG time. . .get's me a modern frame, EFI engine, better transmission. . .basically a much more reliable vehicle with better gas mileage while retaining the vintage style). I feel like the body I'm swapping will not look right with 35's. . .37's would probably look OK, but it's sitting on a stationary chassis right now with 40's and the proportions look good. . .this is why I'm asking.

Thanks for the help!


Well-Known Member
37's are the biggest that I would go. Even then you need to plate the back of the upright's to keep the snouts from ripping out.


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Besides the snouts ripping out (as you mentioned above). . .what are the weak points that are limiting tire size?

Stock U-joints, stock axles, stock , etc.???

Dirty Harry

Well-Known Member
TTB Broncos came with 8.8 rear axles. Not that a 9” is difficult to swap in, but it isn’t what would come from the factory.

You didn’t specify what vintage vehicle you are using, but extended beams might look funny under it. I have a friend with stock length beams under a Jeep Cherokee and he is running 6” glass fenders to cover the tires.

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Well-Known Member
1949 Jeep Willy's P/U. . .

I really like the TTB set-up, but I did think of the aesthetics and a SAS is always an option if I decide it needs it.

I thought the TTB Bronco came with a Ford 9" under it until the 1983 model year (no EFI with a 9". . .at least from the factory which is unfortunate); I've been looking at the 1988 and up models with the EFI 5.8 engine. . .as far as transmissions go I don't know enough about Ford transmission to know which one is more desirable (AOD, manual M50D or M50D-HD, or E40D). Same thing goes for the transfer cases (BW 1356 or supposedly the '93 & up were a NP200 which I have never heard of)???

Swapping a 9" is a lot less time consuming (not to mention cheaper) than swapping an engine or converting to EFI. . .so a 9" swap will definitely be in the cards.


Well-Known Member
IMO 35’s max. Race stock full trucks for years. We progressed to 37’s but had Custom axles etc and it was still a lot of tire on the parts.

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Well-Known Member
One can put big tires a on any Bronco for use in cruising the mall. For serious use much more is required.
Typically with 35s the heater box must be trimmed. With 37s heater box delete or use Ranger version.
Built 9" is most common with the big tires. Cut & turn (Stock width) is needed for these tires. D44 will survive for desert applications and will not survive for rock crawling. All this is usually done with coil overs front and rear.
Stock U-joints etc do not usually fail. 8.8 diffs are weaker than 9". Big tires need wider fenders. Glass in front and push-out in rear. Big tires come with major suspension redesign.
Lots of builds can be copied on "gofastbroncos.com"