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.