350/th400/np208...4.56...what size tire ok?

[Ned Kelly]

Newb type question, but I mostly find info for 700r4 trans and small blocks.
I know my big blocks (having three 454 vehicles), but no experience with sbc 350.

I picked up a 1982 Burb with stock 350/th400/np208 drivetrain.
I thought I'd swap in some spare 4.56 geared one ton axles I have, and was wondering what size tire this would let me go with? Mostly snow, forest trails, and road use.
Actual 35" tire?

 

[obijuank5]

Or even a 37 isn't too bad.

 

[6872xtc]

I would vote for actual 35" tire as the max. I think that the weight of the burb and the axles will be a good load for the engine. Some 35's that measure less than that, would feel better, but then the big axles don't have as much clearance.

 

[TreeFarm]

35" or 37"s would be fine. Are you concerned with highway speed at all? That's where the 4.56 will get you having a 1.1 final gear in the th400. 35"s would put you at 3006 rpm at 65MPH. 37"s drop that down to 2884.

 

[skunked]

With that taller th400 1st you'll probably like the 35" around town. However as mentioned the freeway rpms might be a little much, it's really a personal preference.

 

[Ned Kelly]

Hmmm....maybe i should consider 37", especially if I air down for some of the forest roads.
Probably not a lot of highway driving for this Burb.

 

[sweetk30]

here go play in this site . . .

http://www.grimmjeeper.com/gears.html

 

[Justin V]

My truck has 38's and 4.10's, 700R4, in low range it does fine, definitely not enough gear for highway.

4.56's are only a 12% change from 4.10's.

I'd do a tall 35, or a short 37...

The slightly taller 1st gear of the 400 combined with the extra weight of the burb compared to my truck, i'd lean more towards the 35...

 

[gmc4cw]

I ran a 350/700/208/4.56 ratio with 35's and first would roast the tires but I would hardly use overdrive. wheeling I would run around in lo-2nd or lo-drive just fine. offroad you should be fine, its what you are going to do on-road 90% of the time that matters. dont forget, tires wear out so if its not perfect you can always change it with the next set. or sell em.

 

[Ned Kelly]

Yeah, if I had the 700r4 I'd for sure go 5.13 gears.
Having only a 3sp auto w/o OD seems like being in the stone age.
I know lots of younger guys that won't even consider a square body due to 3sp auto.