What size tires with a 408?

[aichele]

I'm doing some planning for my bronco. The goal is to have it painted by end of summer and start on the engine and suspension. This is frame off restoration that I'm doing myself outside of the paint. I have been looking at 408 builds and think I want to go that route. I have seen multiple comments about the 408 not being great with 33s though.

I live in Phoenix and intend to use it as a daily driver, however I work from home so frankly don't drive a ton. I would like to be able to drive 6 hours or so to Cali though and not worry about it. I was aiming for a very comfortable driver with 33s, a 2.5 lift and 1 in body lift. I'll be running vintage air and explorer serp setup as well. Adding AFR 185s and flopro4 is my current plan as well to pair with the 408. I haven't decided on the tranny yet or gearing. I also am having rolled fenders put on the back, so trimming to fit 35s might be more difficult?

So basically how well does a 408 pair with 33s, or would the 351 be a better fit for everyday driving.

 

[DirtDonk]

It’s not just the engine. In fact, it’s never “just” the engine.
It’s a combination of engine, tire size, transmission choice, and gear ratios in the differentials.
They absolutely positively all have to be taken into account to reach the best results

So for sure decide what tire size you’re going with. No doubts or expectations to change later.
Then decide whether you want a manual or automatic transmission. And either way, whether that’s going to be an overdrive type or not.
Then choose the best gear ratio to work with those things and the engine kind of falls in line as a small part of that equation.
Not really small, but helping you make a decision perhaps on the final axle ratio. Depending on where the engine is going to be happiest.

 

[aichele]

I think ultimately I want 33s and auto for sure. Need help understanding the tranny and gear ratio will mesh best with that. Including if AOD is needed or not on the tranny. It's not like I have a bunch of parts sitting around at the moment, so just trying to find what will work best or be viable.

 

[Madgyver]

gear ratio is key to tire size. engine specs is next consideration in the equation.
take a step back and think about your stance of your bronco.

 

[Broncobowsher]

With something like a 4r70w a set of 4.56 gears would be highway friendly.

I was comfortable running 4.88s and 33s with the same transmission to drive it up to Vegas. 2000 RPM at 60 MPH is a good target.

 

[aichele]

I think I'm getting it.. didn't really know what to search, thanks for reframing it for me.

Broncobowsher I noticed you made multiple comments on other posts around the 351 and 4.56 with a 4r70w working well. Seems to be that or 4.11s.

I think my main takeaway is that the motor doesn't really affect this much and I just need to have the right tire, tranny, and gear combo to hit the rpms at a certain speed. The engine will likely just have a little impact on that, for instance I might go 4.88 if I had a 302, vs 408 4.56 or 4.11s would make more sense

 

[Broncobowsher]

It will depend on how the engine ultimately behaves. It's hard to get a normal gasoline engine to be efficient under load at too low of an RPM. 2000 RPM at highway speeds in a vehicle that has drag to it is about as low as you can go. When you start lacking the torque, add a little more gear. That's how you can get an undersized engine to pull a load.

4.11 is too tall. 4.30 might work, if you stay low, keep the aero and rolling drag down, and cripple the 408 build by building it like a stock engine. Still going to call 4.56 the better choice based on the current data provided and how most 408s are built and run.

 

[aichele]

I really appreciate the insight. Is the cripple the 408 a knock on my plan lol. A regear is always an option if I hate what it ends up as too. The main point I'm taking away other than having a good idea on gear size is that I can go 408 and not worry about 33s vs 35s and just have to plan for it. I'm also aware that I sounds like I want to build a 408 and am fitting everything else to it lol.

 

[Broncobowsher]

I was just watching the latest enginemasters. Can you go too small on a cam? The question was if you could keep making more low end lower and lower if you keep crippling the engine with smaller and smaller came. What they came out with is once you shift it to a low point, going to a smaller cam won't make more low end torque but only kills everything else. There is a basement to where you can put the torque curve.

 

[nvrstuk]

Everybody worries about torque when building a 393+ cuin stroker--I used to also. Not anymore. You have to realize that you will have SO much MORE torque with a 408 or larger stroker that most undersize the cam like Bowsher was saying. I've made that mistake before-long time ago.

408, 33's, & an OD trans for your street trips whether it's a 4r70 or 6r80 and 4.56 gears and you'll be good. The nice thing about the 6 spd is your gear splits are much closer together so when you shift down it's MUCH less noticeable and hence, smoother. Nice to have for street cruising.

You can not go wrong with the 408- just can't. Have fun with your build!

 

[MonsterBIlly]

I'm doing some planning for my bronco. The goal is to have it painted by end of summer and start on the engine and suspension. This is frame off restoration that I'm doing myself outside of the paint. I have been looking at 408 builds and think I want to go that route. I have seen multiple comments about the 408 not being great with 33s though.

I live in Phoenix and intend to use it as a daily driver, however I work from home so frankly don't drive a ton. I would like to be able to drive 6 hours or so to Cali though and not worry about it. I was aiming for a very comfortable driver with 33s, a 2.5 lift and 1 in body lift. I'll be running vintage air and explorer serp setup as well. Adding AFR 185s and flopro4 is my current plan as well to pair with the 408. I haven't decided on the tranny yet or gearing. I also am having rolled fenders put on the back, so trimming to fit 35s might be more difficult?

So basically how well does a 408 pair with 33s, or would the 351 be a better fit for everyday driving.

It doesn't matter dude. You ate mixed up. The engine doesn't matter as much as the gears..
If you wanna run 35 you should have 4.56 gears min buy better would be 4:88s
However you should pick out your trans first. The gears eill.aalways differ.

 

[hossbronco]

Don’t forget to take into account that while you may be starting with 33s, it’s a biological fact that you’ll want bigger tires in the future. I remember the day I thought 35” tires were as big as I’d ever want on an EB. Now I’m working on a plan to stuff in 40” tires. While I’m not suggesting you’ll ever want 40” tires, 35s look dang-good on an Early Bronco.

Oh, and at some engine vendors, the 427 costs as much as the 408.

 

[Madgyver]

Ask yourself, what can I build? What am I capable of building?
and then "Build It!"

Nothing will stop you... 408 with big C heads, Tremec 4050, 4.88-5.13 gears, 37" in a rust bucket that gets driven daily... on or off road

 

[sprdv1]

I really appreciate the insight. Is the cripple the 408 a knock on my plan lol. A regear is always an option if I hate what it ends up as too. The main point I'm taking away other than having a good idea on gear size is that I can go 408 and not worry about 33s vs 35s and just have to plan for it. I'm also aware that I sounds like I want to build a 408 and am fitting everything else to it lol.

Wealth of knowledge and input on here..

 

[sprdv1]

Ask yourself, what can I build? What am I capable of building?
and then "Build It!"

Nothing will stop you... 408 with big C heads, Tremec 4050, 4.88-5.13 gears, 37" in a rust bucket that gets driven daily... on or off road

Amen.. you can do anything you set your mind to