1979 Crew Cab Dually 496 - Tire Wizard Needed

[mrburitto]

Hello Everyone!

I just picked up this beauty and am getting it ready to be my primary tow vehicle for a toy hauler. The 454 was stroked and bored to a 496. Its got a TH400. 120,000 miles with only 60,000 since the engine was redone. Its got a lot of little custom touches done by the PO who was a GM mechanic for years so everything was done right. Ive got a lot of stuff I want to do to it, but unfortunately I havent won the lottery yet so Im starting with the essentials and hope to have her on the road soon.

First on the list is tires that will actually hold air. This is my first dually and Im having trouble figuring out what to go with. I dont know exactly how much tongue weight my future toy hauler will have but I obviously want my tires to be well above that. I bought some Falken AT LT235/85/16s that I really like but when I put them on last night the rears only have about 1/8th of an inch of space between them with the truck still in the air lol. What I don't get, it seems like every other forum post I find guys are running this same size though. So now I have three options that I can see:
1.) Try a different brand tire and pray that somehow I gain an inch of gap (unlikely, and I actually really love these tires. They look awesome)
2.) Get a spacer ( I dont like this idea because I dont want to shift the load on the bearing or do anything that will make it more dangerous to haul around my kids with the toy hauler)
3.) Go with a 215/85/16 tire which would mean I have to go with a different manufacturer and everything. Not to mention being skinny and (I think) looking bad. To be honest, Im having a hard time finding pictures of what the 215's will look like on it but i dont think I will like it lol.

So thats where I am, any help/guidance is appreciated. If anyone has pictures of their dually with 215s I would appreciate a look! Or actually any size tire, just so I can get a better idea of what I want lol. I threw in non-tire pics too cause I havent started a build thread yet and shes too pretty not to show off

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

 

[Grit dog]

Sweet looking rig!
Primary tow rig, punched out old big block with a 3 speed sounds like torture all around though. Physical (uncomfortable and slow), mental (loud and slow) and financial (gas pump).
Cool looking truck though! I like it!

 

[Lu Blunt]

I have a few squarebody duallys and have ran 235/85r16 on most of them. What tire pressure are your running? Gotta keep the pressure high so the side walls don’t touch on heavy loads. Here’s a pic of my 84 k30 with 215/85r16. Its sitting alittle low due to worn out leaf springs. And a pic next my other brown dually with 235/85r16. Not at home but I can get better pics later if needed

You must be registered for see images attach

You must be registered for see images attach

 

[mcarlo86]

235 85R 16's are a very common tire size on duallys. That is what I put on my P30 chassis 78 motorhome. Most of the chevy C30's from that era came with 7.50-16's and they are pretty close to a 235 85 16. 215's are shorter, so I would stick with the 235s. Just make sure you have enough air in them and they should be just fine.

 

[mrburitto]

Sweet looking rig!
Primary tow rig, punched out old big block with a 3 speed sounds like torture all around though. Physical (uncomfortable and slow), mental (loud and slow) and financial (gas pump).
Cool looking truck though! I like it!

Lol ya im aware. I plan on putting a Holley Sniper to squeeze out a couple more MPG, but when you do the math, I pay $40 a month in insurance on this vs 200-300 for a new truck. I paid 5K for this vs 60K for a new truck. Just the difference in insurance payments more than makes up for the gas mileage assuming I average one trip a month. Not to mention the overall cost and the cool factor

And Im thinking Ill convert it to a 4l80E or put in a gearvendors for overdrive

 

[mrburitto]

I have a few squarebody duallys and have ran 235/85r16 on most of them. What tire pressure are your running? Gotta keep the pressure high so the side walls don’t touch on heavy loads. Here’s a pic of my 84 k30 with 215/85r16. Its sitting alittle low due to worn out leaf springs. And a pic next my other brown dually with 235/85r16. Not at home but I can get better pics later if needed

Thanks! I should clarify, they are not rubbing at the moment, but i only have about an 1/8th of an inch gap in some places where the agressive sidewall treads are. If they didnt have the knobs on the side, I would have about half an inch, maybe a little less. And its not even on the ground yet.

 

[shiftpro]

Lol ya im aware. I plan on putting a Holley Sniper to squeeze out a couple more MPG, but when you do the math, I pay $40 a month in insurance on this vs 200-300 for a new truck. I paid 5K for this vs 60K for a new truck. Just the difference in insurance payments more than makes up for the gas mileage assuming I average one trip a month. Not to mention the overall cost and the cool factor

And Im thinking Ill convert it to a 4l80E or put in a gearvendors for overdrive

Is this awesome truck running the 4.10 gears?
A 4L80 would be awesome but just a reminder you would need an electronic shift controller, min $500.

A note for all on GearVendor.... keep an eye open for late 70s-80s GM motorhomes. Many came with a GearVendor and the price of an old motorhome is often less than a new GearVendor.

 

[mrburitto]

235 85R 16's are a very common tire size on duallys. That is what I put on my P30 chassis 78 motorhome. Most of the chevy C30's from that era came with 7.50-16's and they are pretty close to a 235 85 16. 215's are shorter, so I would stick with the 235s. Just make sure you have enough air in them and they should be just fine.

So maybe its worth my time to just get a different brand/model and see if i have enough clearance? BTW, im going on what I found online, NHTSA says you have to have 1" of gap. Most guys say about 3/4". I think I would be happy with 3/4"

 

[mrburitto]

Is this awesome truck running the 4.10 gears?
A 4L80 would be awesome but just a reminder you would need an electronic shift controller, min $500.

A note for all on GearVendor.... keep an eye open for late 70s-80s GM motorhomes. Many came with a GearVendor and the price of an old motorhome is often less than a new GearVendor.

WHATT? Why have I never heard about gearvendors in those motorhomes before? Thanks! I will definitely be looking now lol.

It is running 3.73 gears. Which I dont see a problem with at all considering its a 496. I dont think ill be needing any more torque lol. Maybe Im wrong though...

 

[Big Chip]

That’s a sweet truck. Let’s see those bucket seats and console setup.

 

[mrburitto]

How much gap do you guys have between your tires?

 

[mrburitto]

That’s a sweet truck. Let’s see those bucket seats and console setup.

Heres the seats and console. He also put in the overhead console from a suburban. Early 80s I think. BTW, the seats were perfect when I got it. Just getting in and out they have started to tear from sun rot though Getting them reupholstered is also high on my list of things to do so that I dont mess up the foam at all

You must be registered for see images attach

You must be registered for see images attach

 

[bucket]

How much gap do you guys have between your tires?

My truck has spacers between the rear wheels. It's never caused an issue and the outside duals have seen some abuse too.

 

[mrburitto]

My truck has spacers between the rear wheels. It's never caused an issue and the outside duals have seen some abuse too.

are they slip on spacers or the kind that bolt on and then have their own studs?

I was thinking about getting a 3/8" slip on spacer. That might give me just enough clearance. the other problem is i dont know how much they would flex if i put 5K lbs tongue weight on it...

 

[bucket]

are they slip on spacers or the kind that bolt on and then have their own studs?

I was thinking about getting a 3/8" slip on spacer. That might give me just enough clearance. the other problem is i dont know how much they would flex if i put 5K lbs tongue weight on it...

They are the bolt-on type with their own studs. 2" thick, to run big tires.