Why no Magnum 500s on Hemi cars

[Cncguy]

Was looking at old option literature for 69 Chargers, and it says Magnum 500s NA on RTs with  Hemi. Why is this? Could these not handle the power of a Hemi? What were the factory wheel options on a Hemi car?

[chargd72]

I could take a guess.  The Magnum 500s didn't allow as much air in as slotted mags or ralley wheels to cool the brakes. 

[6bblgt]

1968 & 1969 HEMI b-bodies had 15" wheels STANDARD and Chrysler Corp. didn't offer a 15" "MAG" wheel at the time, other than the short lived 1969 "recall" wheel.
1967 HEMI cars could be had with 14" "chrome ROAD wheels" (MAGNUM 500s).
1970/'71 HEMI b-bodies could be had with 14" "chrome-style ROAD wheels" (w/trim rings)

[Ghoste]

What he said. 

[hemi68charger]

Now "WHY" they put 15-inchers on 426 Hemi equipped cars is a mystery to me.. Maybe for cruising/rpm issues? I personally would like to know myself.........

[6bblgt]

it probably had something to do with a specific tire's limits or load ratings

why do they put E series/rated tires on diesel trucks

[hemi68charger]

it probably had something to do with a specific tire's limits or load ratings

why do they put E series/rated tires on diesel trucks

Does that mean C-body yachts got 15"? Most I have seen are 14".... guessing I am.......

[Ghoste]

Or raising the bottom line of the car?

[ws23rt]

I'd like to know the thinking as well about why the 68-69 hemi b body's called for 15" wheels?

If less side wall thickness was better (for whatever reason) than why not 16"?

[TUFCAT]

My guess is with Troy,  I've heard it was done for gear ratio and RPM more than anything.   ...especially since you could get a 3.23 auto with a Hemi.

[ws23rt]

Would not the tire OD be independent from the wheel dia?  Some people use 20" and more but maintain ride height by the tire they chose.

[TUFCAT]

Would not the tire OD be independent from the wheel dia?

In theory your point is still true today....upsizing the rim 1" changes tire profile.  Maybe it was something about that?  

[FJMG]

 
F70-14 OD 26.2"
F70-15 OD 26.9"

I am sure these numbers vary though.

[ws23rt]

My thinking tells me that with a smaller wheel dia. their is less wheel to tire seating area.  --More likely to spin the wheel on the bead?--
But since the call out was for hemi equipped cars and not 440s it seems like the torque issue may not be the reason someone made the decision.

[HPP]

Because a 15" diameter tire has more surface contact area with the road than a 14" tire.  This is why NHRA limits allowable tire diameter on the Pro classes. So why not 16" or bigger, well, that was beyond the available performance technology of the day and those larger size rims were regulated to trucks with even stiffer and lower traction tires than what was already on these cars.

[ws23rt]

Because a 15" diameter tire has more surface contact area with the road than a 14" tire.  This is why NHRA limits allowable tire diameter on the Pro classes. So why not 16" or bigger, well, that was beyond the available performance technology of the day and those larger size rims were regulated to trucks with even stiffer and lower traction tires than what was already on these cars.

The question here is about the wheel dia. not the tire dia. ??

[HPP]

...and the original question was why no magnums, but it evolved into why 15s?

It matters because wheel diameter relates directly to the tire diameter installed on it.  Look at FJMG's reply, F70x14 vs F70x15. That .7" extra diameter could translate into 1.5" of additional rollout on the ground. That's important and Chrysler engineers knew it.

The whole +1 concept of sizing didn't come around until the '70s when tire manufacturers were improving construction and compounds to allow the shorter tires to have better grip and better lateral g capability.

[TUFCAT]

15" road wheels (magnum style) were available on Ford products in 1969.  I believe the same OEM vendor "Motor Wheel" made both the 14" and 15" wheels....  I don't know why Chrysler didn't get in on the action?  

[6bblgt]

15" road wheels (magnum style) were available on Ford products in 1969.  I believe the same OEM vendor "Motor Wheel" made both the 14" and 15" wheels....  I don't know why Chrysler didn't get in on the action?  

Like the Mopar world - everyone puts 15" tires/wheel (or larger) on their car.
The ONLY 1969 FORD musclecars that got 15" Magnum/other wheels (15x7.0" w/F60-15 Goodyear POLYGLAS GT) from the factory were the SHELBY, BOSS 302 & BOSS 429 Mustangs.

The ONLY other 1968-'69 (non-full size) musclecars that got 15" wheels from the factory were the '69 HURST/OLDS (15x7.0" w/F60-15 Goodyear POLYGLAS GT) & Z/28s (15X6.0" w/E70-15 NYLON).*

* & 'Vette "if" you consider it a musclecar (15x8.0" w/F70-15 NYLON).

[6bblgt]

& somehow I forgot to add:

1969 A12 Road Runners & Super Bees (15x6.0" w/G70-15 Goodyear POLYGLAS)
1968 SHELBY Mustangs GT350/GT500 (15x6.0" w/E70-15 NYLON) GT500KR (15x6.0 E70-15 Goodyear POLYGLAS)

[TUFCAT]

6bbl, you are 100% correct.  I should have said "some" Fords.   Starting in '70 the 15" Magnum styled road wheels was offered on more Mustangs and even Torino GT and Torino Cobra had them available.  More and more muscle cars were sporting new 15" wheels in '70. Of course we know 15" rallyes came out for Mopar, and even AMC got on the 15" wheel bandwagon with the Rebel Machine in '70

[odcics2]

 
The hemi cars had the 15" wheels for oil pan clearance. 

[TUFCAT]

The hemi cars had the 15" wheels for oil pan clearance. 

That makes sense!  thanks

[8WHEELER]

Also, the 66-68 chrome Magnum's on mopar's, were offered at 14 x 5.5 only. So I think the width came into play somewhat for the 68 model year Hemi car.

The Ford Chrome Magnums were offered at 14 x 6 and 14 x 7, I believe the 14 x 7 started in 67 or 68.

Dan

[6bblgt]

Also, the 66-68 chrome Magnum's on mopar's, were offered at 14 x 5.5 only. So I think the width came into play somewhat for the 68 model year Hemi car.

The Ford Chrome Magnums were offered at 14 x 6 and 14 x 7, I believe the 14 x 7 started in 67 or 68.

Dan

No MAG wheels from Chrysler Corp. in '66.  The '67-'68 chrome "ROAD" wheel was 14x5.5" on b-bodies & 14x6.0" on c-bodies.  IT'S ALL ABOUT THE TIRE! There are many 1970 HEMI b-bodies that came from the factory with "ROAD" or "RALLYE" wheels that were 14x5.5" with F70-14 Goodyear POLYGLAS tires (in '68 the F70-14 was a much less capable tire - GOODYEAR SPEEDWAY)

Mustang did NOT have a 14x7.0" wheel until 1970 & it was NOT of the MAGNUM 500 design.

[8WHEELER]

I have seen so many 66 Hemi Chargers, over the last 35 years with the Chrome magnum wheels, I assumed they came that way factory   

Good to know on the C-Body size, I have at least six sets of 68 Chrome Magnum's, and all are 14x5.5 so all b-body wheels.

And the only repop size available are 14x6. I have two sets of them.

Dan

[6bblgt]

And the only repop size available are 14x6. I have two sets of them.

reproduction wheels are available in many sizes, but not 14x5.5" if that's what you meant 

The "spinner" wheel cover was STANDARD on the '66 Charger.  No other cap/cover/wheel was FACTORY available.

[8WHEELER]

And the only repop size available are 14x6. I have two sets of them.

reproduction wheels are available in many sizes, but not 14x5.5" if that's what you meant 

The "spinner" wheel cover was STANDARD on the '66 Charger.  No other cap/cover/wheel was FACTORY available.

That is what I meant, I have many repop sets of 15x8's and 15x7's as well, having four of these cars, I have collected many
sets over the years, some look better with 15x8's, and the bone stock cars I keep stock. My 74 Dart Sport 360 has 15x7
magnum's, Most people think it looks better than the Rallys.

Dan

[charge69]

Well, I have all 5 original 15" steel wheels for my Charger and 4 new OEM wheel covers that also came on my Charger but, I am kinda fond of the "day 2" look and the Cragars with wider tires.

[odcics2]

Also, the 66-68 chrome Magnum's on mopar's, were offered at 14 x 5.5 only. So I think the width came into play somewhat for the 68 model year Hemi car.

The Ford Chrome Magnums were offered at 14 x 6 and 14 x 7, I believe the 14 x 7 started in 67 or 68.

Dan

No MAG wheels from Chrysler Corp. in '66.  The '67-'68 chrome "ROAD" wheel was 14x5.5" on b-bodies & 14x6.0" on c-bodies.  IT'S ALL ABOUT THE TIRE! There are many 1970 HEMI b-bodies that came from the factory with "ROAD" or "RALLYE" wheels that were 14x5.5" with F70-14 Goodyear POLYGLAS tires (in '68 the F70-14 was a much less capable tire - GOODYEAR SPEEDWAY)

Mustang did NOT have a 14x7.0" wheel until 1970 & it was NOT of the MAGNUM 500 design.

68-69 Hemi cars got a 15" wheel for oil pan clearance. In 70 the standard wheel for a hemi was a 14x6".   

[6bblgt]

68-69 Hemi cars got a 15" wheel for oil pan clearance.

if that was true  - Chrysler could've cranked the torsion bars up for the same effect (& what changed for '70 that this was no longer needed or desired)

In 70 the standard wheel for a hemi (b-body) was a 14x6".  

CORRECT!  ..... but if 14" W21 "RALLYE" or W23 "ROAD" wheels were ordered - the wheels were 14x5.5"

[ws23rt]

If the Od of an F70-14 is 26.6'' and F70-15 is 26.9" as FJMG said that would put the car .35" higher (or just a bit less than 3/8") with the 15" wheel.
The width of the rim would not change the diameter of the tire a relevant amount.

[6bblgt]

26.9-26.6=0.3" diameter

Coker Tire shows their reproduction Firestone WIDE OVAL tires as:
26.90"(F70-15) - 26.20" (F70-14) = 0.70"

Kelsey Tire shows their reproduction Goodyear SPEEDWAY tires as:
26.51"(F70-15) - 26.20" (F70-14) = 0.31"

Kelsey Tire shows their reproduction Goodyear POLYGLAS tires as:
27.09"(F70-15) - 26.45" (F70-14) = 0.54"

half that dimension would be raising the car from the centerline of the wheel (or the oil pan)

[ws23rt]

26.9-26.6=0.3" diameter

Coker Tire shows their reproduction Firestone WIDE OVAL tires as:
26.90"(F70-15) - 26.20" (F70-14) = 0.70"

Kelsey Tire shows their reproduction Goodyear SPEEDWAY tires as:
26.51"(F70-15) - 26.20" (F70-14) = 0.31"

Kelsey Tire shows their reproduction Goodyear POLYGLAS tires as:
27.09"(F70-15) - 26.45" (F70-14) = 0.54"

half that dimension would be raising the car from the centerline of the wheel (or the oil pan)

You are right--in the difference of 26.9 and 26.6.  I miss. typed the dia.  that FJMG wrote. ----He showed the F70-14 to be 26.2" dia.  OOps. That is what I meant to say.
My point is that the difference in height of the car is minimal and makes me wonder about the motive for giving the oil pan more room as being the reason for the rim size question.

[Mike DC]

     
The oil pan clearance isn't an issue when the tire is inflated and the suspension is at ride height.  But the factory had to build cars for the 100% real world. 


Imagine driving hard into a curb with both front wheels, like at full speed.  The tire sidewalls will compress fully.  At the same time, the front suspension will be bottoming-out against the rubber stops on the LCAs.  Now the front wheel rim height is the only thing holding the chassis off the pavement. 

With the Hemi oil pan/skid plate sticking down an inch farther than stock, running the bigger wheels was the least they could do.  Even with the 15's only half of that extra inch is on the bottom side of the rim.

[ws23rt]

   
The oil pan clearance isn't an issue when the tire is inflated and the suspension is at ride height.  But the factory had to build cars for the 100% real world.  


Imagine driving hard into a curb with both front wheels, like at full speed.  The tire sidewalls will compress fully.  At the same time, the front suspension will be bottoming-out against the rubber stops on the LCAs.  Now the front wheel rim height is the only thing holding the chassis off the pavement.  

With the Hemi oil pan/skid plate sticking down an inch farther than stock, running the bigger wheels was the least they could do.  Even with the 15's only half of that extra inch is on the bottom side of the rim.

The extra half of an inch on the bottom side of the rim is not what raises the car. It's the extra .35 in. on the bottom of the tire.

My only point about all this is that the wheel/rim diameter is not what determines the height of the car.  It's the tire dia. on that wheel.
With the F70-14 tire (26.2" dia.) the car is .35" closer to the ground than it is with a F70-15 tire.(26.9")

If the car had an 18" rim with a 26.2"dia tire it would not be 2" closer to the ground because of the rim size. It would be the same.
This of course discounts any difference in side wall flex between the two examples.

With the tires fully compressed as when hitting a curb their would be a slight difference. I wonder if this is what they had in mind when the decision was made about the rim size?

[Mike DC]

ith the tires fully compressed as when hitting a curb their would be a slight difference. I wonder if this is what they had in mind when the decision was made about the rim size?

That's my point.  If the rim itself gets 1" bigger then that holds the chassis another 1/2" farther off the pavement no matter what.  



We don't think about this stuff.  But the factory does.  Not only that, the whole undercarriage of the car is designed to minimize damage if the whole car gets forced over a curb.

Look at how the stock K-frame's leading edge is curved, and how that affects the side-view angle it presents a curb.  (The aftermarket never worries about this, do they?) 

Look at how the front edges of the rear subframe rails are sloped upwards to the floor.   

There are other things to hit under the chassis, exhaust, radiator support, etc.  But all that stuff is more "crushable" compared to the subframes & K-frame.