[vortec710]

Looking to see if anyone has tried a taller tire & wheel combination for over the road travel, what is the tallest tire/rim that will fit into a Chevelle rear wheel housing, want to cut down the RPM's for distance travel..currently a El Camino with 15x7 wheels and 235x70Rx15 radials, 28" tall. Pull the current wheel/tires off, put in bed/trunk and put on a taller tire for long distance, change back when trip done for local use, for occassional use only, tire width not too important, it's currently a BBC and TH400 with a 3.42 gear, don't want to change to an O.D. set up, If you've done this or seen it done successfully would like to hear about it. NOT GOING TO CHANGE THE TRANNY.

 

[Leadhead]

I run 255/70R15s on the back of mine. 29" tall.

 

[427L88]

a 31" tall tire wouldnt fit my 67. I run 275/60/15 @ 27.75". 275/70s maybe. Maybe Lead's 29" dia will work. Each 1" is like .2o in ratio, so 2" = -(0.40) or so.

Unlike my garage built 427, I DO NOT like to run the MJ467 up too high and try to go speed limits @ approx 3000 rpm tops. ( 70 is like 3050) WIth the 427 I ran her at 3500+ for hours going 80.

PS I dont know about you, but I would have to save 1000 gallons of fuel to justify an OD. Thats ALOT of running around!

 

[Leadhead]

I was planning on trying 275/70s once I get mine back together.

 

[vortec710]

Looks like I'd better slide myself underneath with a good light and ruler to see just how much clearance my 28" diameter tires have now, I suspect a 75 series tire MIGHT be a candidate, I still have some nice 15x6 and 15x7 rallys tucked away. I'd like to keep the 70 mph RPM's down as much as possible, want to preserve my MJ467 also, any fuel savings would be a secondary benefit. I also have a converted Holley 1850 (585 cfm) with center pivot bowls, a sec. jet plate conversion with an electric choke and sec. diaphragm quick change conversion I might consider for OTR use and put the Holley 770-SA in the bed, also a Summit 780 cfm annular discharge that might be an OTR candidate. Nice thing about El Camino's is bed storage and the dog doesn't mind sleeping near the vehicle and he's a light sleeper.

 

[427L88]

Hey, my MJ467 bangs out 16 mpg when I go the speed limit and not pass too often! Holley 850 DP. How bad could running 3000 rpms @ 20" Hg be ?!

 

[Kirk's67SS]

Since you have a 1970 i would think you could fit a 30"+ Tire on a 15" Wheel
............................ Current = 235/70/15 .................... to .............255/75/15 ................... or .. 265/75/15

• Section Width = ................ 9.25" ............................................. 10.04" ................................ 10.43"
• Tire Height = .................... 27.96" ............................................ 30.06" ............................... 30.64"
• Tire Circum = ................... 87.84" ............................................ 94.44" ............................... 96.26"
• Rev / Mile - ...................... 721.31 ........................................... 670.9 ................................. 658.22
  

If you can get a Tire you like and in the Size

 

[Kirk's67SS]

If you are look to also change your Carb for one with better Gas Mileage
look at a Street Demon as it works like a Quadra Jet but better
// 2 Front Small Barrels for Cruzin & the Large Back ones for GOGO Times
Demon Carburetion 1901: 625 cfm Street Demon Carburetor 1-3/8" Primary Throttle Bores | JEGS 625cfm
Demon Carburetion 1904: 750 cfm Street Demon Carburetor 1-11/16" Primary Throttle Bores | JEGS 750cfm

 

[cage2592]

I'm running 305/35r20 on the 70. 28.4" overall Dia. I'm at 85mph @ 3000rpm. Gearing is in my signature

Mike

 

[cricket]

I run 255/70R15s on the back of mine. 29" tall.

Are you running that tire on a 8 inch wide wheel, with a 4.5 inch back spacing?

 

[Leadhead]

Yep stock vette ralleys. Plus a wider 68-70 Olds 12 bolt rear.(was in the car when I bought it)
I'm sure it would fit even better if I had the right rear end.

 

[suprdave1]

What rpms you running at 70 with a 3:42?

 

[vortec710]

If you are look to also change your Carb for one with better Gas Mileage
look at a Street Demon as it works like a Quadra Jet but better
// 2 Front Small Barrels for Cruzin & the Large Back ones for GOGO Times

I’d rather try out my “paid for” carbs first, but your concept appears valid, kinda a little more modern variant of the old Holley 3-bbl.

 

[vortec710]

What rpms you running at 70 with a 3:42?

About 3200 rpm’s

 

[Robinls5]

I have been running 225 X 70R X 14 Redlines on stock 14" - 70 SS wheels, For over 15 years on my wagon.
468 -700R4- 3:07-12 bolt. At 75 MPH in Electronic cruise the 468 spins 1950 & 19 MPG with out the A/C operating. It drops 1 or 2 MPG with the air ,, But who cares! As of Aug.-2021,,, I has been driven 49.000 road miles with this Combo. NO issues so far. It has been driven to Fla. to Canada. PA. to Texas and Chevelebration 13 times. It is one of the nicest " SS " fake or FRAUDS out there. All parts are 70 and all parts are date coded.
Bob ( C U in the " WINDY " ) MCACN

 

[O'Man]

Yep stock vette ralleys.

Leadhead and Cricket: Please clarify something for me. Are stock 8 inch Vette Rally wheels 4 inch backspace or 4.5 inch backspace? I always thought they were 4 inch? I believe Cricket says 4.5 but somehow I have 4 inch stuck in my head for the backspace number.

Thx
O'Man.

 

[suntreemcanic]

If your are worried about RPMs slip some 3.08s in.

 

[Leadhead]

Leadhead and Cricket: Please clarify something for me. Are stock 8 inch Vette Rally wheels 4 inch backspace or 4.5 inch backspace? I always thought they were 4 inch? I believe Cricket says 4.5 but somehow I have 4 inch stuck in my head for the backspace number.

Thx
O'Man.

Unfortunately I'm working late, and wint be able to get to it today. But everything I'm seeing says that the stock 69-82 15x8 vette rallyes were 4" back space.

 

[vortec710]

If your are worried about RPMs slip some 3.08s in.

NOT INTERESTED IN CHANGING THE GEAR OR THE TRANSMISSION...THIS IS FOR OCCASIONAL USE ONLY.

 

[toofastforyou]

I have some 285-45-20's on the rear of my Chevelle which are 30" tall...

Claude.