"Back in the day" when we were dealing with bias ply tires, there was not so much rotational mass (weight) on the outside diameter of the tire. The most of the weight of the wheel was the wheel itself which by definition was closer to the center of rotation. The wheels were narrow - frequently 4.5 to 5 inches wide. Roads were rougher and speeds were lower. Suspensions were probably less sensitive to transmitting road feel.
Balance became more of a problem when we went to bias belted tires in the early 70's and then radials with steel belts on the outer diameter creating a much different weight distribution within the tire / wheel assembly. These also came with wider wheels (6 to 7 inch). And roads were improving as well as car suspensions. Speeds were increasing.
Now think of an individual tire - the reason we balance them is that they are imperfect with respect to weight distribution - there has to be a splice in each ply where the carcass is built up. This results in a local area where there is overlap and non uniform weight. The rubber mixture may also be less than uniform density - after all it is a mixture that is extruded into sheets that are also spliced. So if a tire is perfectly uniform, it is unusual. And the rims may be imperfect also as steel rims are frequently welded together and aluminum wheels may have nonuniform density due to casting.
A tire can be modeled as a rotating circular disc - but now think not of disc representing the tire geometry but the disc representing its mass (weight) distribution. It you tilt the disc to where the disc runs thru the center of mass (weight), the heavy spot causes the plane of the disc to tilt from the disc representing the center of geometry of the tire which is still the center of rotation. But the tire wants to rotate with the plane representing the center of mass and hence wobbles creating the vibration we feel from imbalanced tires.
In rotational bodies there is a resonant frequency which is a function primarily of outer diameter and rotational speed. When imperfect objects rotate they create forces due to the imbalance, but these forces may be relatively small at speeds not near the resonant frequency. Typically for older vehicles this was roughly 60-65 mph so you would feel the worst vibration at that speed. The frequency is purely a function of revolutions per minute and hence tire diameter and vehicle speed. The vibration will be worst at this speed - and you may actually be able to reduce the severity of the vibration by increasing or reducing speed - though it will probably still be present.
We balance tires and wheels to make the car think the assembly is perfect and the planes of rotation and mass are the same. But how do you do that when heavy spot may be on inside or outside of tire and there may be more than one at different placed around the tire.
The first fix was to add a weight opposite the heavy spot - this worked at low speeds but failed at the resonant frequency (specific vehicle speed). In reality, a single point balance or even a 2 point balance on the back only has a 50-50 chance of aggravating the problem - If you are unlucky and the heavy spot is on the front (outside) of the wheel and the balance weights are opposite and on the back (inside), you have increased the effect of the tilt of the plane representing the center of mass.
We then went to a "4-point" balance to try and better distribute the heavy areas compensating for the imbalance. In this method you put 2 weights on top and 2 on bottom spaced apart so that there were really 3 heavy spots spaced around the tire - this worked pretty well as speeds increased with bias tires.
But the first belted tires with more weight and more splices on the outside diameter required more sophistication - hence the development of on car rotational balance and eventually computer spin balance.
Sorry for the history lesson and the tech-speak, but I tried as best I could to make it understandable. Hope this helps.
Edward Mills Antique Tractors 1930-1960 Antique Cars 1960-1985On 7/29/2019 1:05 AM, 'Rich Barber' c300@xxxxxxx [Chrysler300] wrote:
??For appearance sake, I directed my tire guy at the time to mount all weights on the inside of the 15??? OEM Motor Wheel wire-spoke wheels.?? H said he would, but the wheel would not be dynamically balanced. I ran those old Bias-ply Remington???s a lot of miles at high speed and never felt any pronounced out-of-balance sensation.?? I believe the computerized wheel balancer directs the technician how much weight and where, ,including inside or outside.?? I don???t understand the physics of splitting the weights inside and/or outside but there must be a good reason.?? Tire and wheel guys:?? What, if anything do we lose by placing all weights on the inside??? And, why split the weights inside and out anyway?
??
Rich Barber
Brentwood, CA 105F today.
??
From: Chrysler300@xxxxxxxxxxxxxxx On Behalf Of Noel Hastalis cpaviper@xxxxxxxxxxx [Chrysler300]
Sent: Sunday, July 28, 2019 9:59 PM
To: Curtis Roys <curtisaroys@xxxxxxxxx>
Cc: Chrysler300 <Chrysler300@xxxxxxxxxxxxxxx>
Subject: My additional "2 cents worth" Re: [Chrysler300] American Classic radial tires??
??
Curtis and Group,
??
One final 'road-tested' comment from me re the 235/75R14 American Classics I'm running on my 300-F. Just drove back to Chicago from our wonderful Minneapolis Fall Meet tonight - have now put 4,300+ miles on my tires since having them mounted on the F's stock 14"x6.5" steel wheels in April, a few days before heading down to Texas for our Spring Meet. Homeward bound through northern Wisconsin, with strong crosswinds and torrential rain for 100+ miles tonight, in addition to the heavy rains I encountered for a good part of the trip to/from Dallas, these tires have performed very well. There's no sense of fighting the car to keep it stable through these heavy downpours. I'm very happy with their performance.
I purchased my 4 tires through a Coker special promotion at a Mecum auction last fall - cost including free shipping and road hazard warranty was about $1,040. Whitewalls are 2 1/2". If your purchase them, be sure to read the online instructions for mounting - including the recommendation that wheel weights be only mounted on the insides of the rims, so as to not blemish the whitewalls.
??
Noel Hastalis
Burr Ridge, IL
??
On July 28, 2019 at 8:00 PM EMills_ATC <millserat@xxxxxxxxxxxxx> wrote:
Sorry for late reply - probably already solved, but here are some data I have compiled from 1960's to 2015 on tires.
First I will list 8.00-14 as it evolved to P215/75R14 (P/225/70R14), noting that P215/75R14 is largest 14 inch whitewall (Narrow White) in current full scale production as of 2019. (Hankook Optima H724 price around $65-80). There are other specialty tires ($200-300 range) including 8.00-14, G78-14, and P215/75 R14 including wide whitewalls, but for the most part these are limited production specialty runs, in some cases using outdated equipment. There is also an American Classic in P235/75R14 in whitewall (Wide and Narrow White?).
I will note that in early days, to provide a soft ride, tire design was based on 24 psi, frequently with note in fine print to increase pressure (up to 32 psi) for sustained high speed or increased load. If I recall correctly the 24 psi assumed driver plus 2 passengers and 1 suitcase. Anything more moved you to higher load. And Speed limits were mostly assumed to be 60 mph. Later load capacities were based on 32 psi, and most current standard load range radials are based on 44 psi - so dont assume load ratings are directly comparable - and it your rims are old beat up rusty things, dont assume you can go to 44 psi safely.
Also, belted and later radial tires tend to have more flexible sidewalls and give lower ride height for a given diameter. This is reflected in the SLR (Static Loaded Radius) column if I had any data from manufacturers data sheets. Most likely your 8.50-14 had a SLR of about 13 in, while a P215/75R14 would be closer to 12 inches and even the P235/75R14 is likely to be only 12.5 to 12.6 inches, hence lowering the car about a half inch despite being oversize to the P225/75R14 equivalent to the original 8.50-14
Second I will list the 8.50-14 to P225/75R14 specifications as these are more likely applicable to C-body cars. Unfortunately the last P225/75R14 I know of were produced by Cooper in 2006.
Lastly I will provide data for 9.00-14 to P235/75R14 - again, I believe the American Classic is currently available in the P235/75R14 as of 2019.
??
SIZE
MFG
TYPE
Sidewall
OD
LOAD
RPM
LR
SWid
RimW
TWid
SLR
Cost
Source
8.00-14
BFG
Deluxe Silvertown (3-60 Mfg Spec)
27.54
7.5
5.5
4.53
12.79
??
1960 BFG
8.25-14
GoodYear
Power Cushion (Mfg Spec)
27.56
8.2
6
??
??
??
1967 Goodyear
205R14
Michelin
XWW (Mfg Spec)
26.9
1620
778
8.1
6
??
12
??
Michelin 1979
G78-14
General
Belted Jumbo 780 (OE)
27.27
8.54
6
??
12.47
??
General 1971
GR78-14
Michelin
XWW (Mfg Spec)
26.8
1620
782
8.4
5.5
??
11.8
??
Michelin 1979
P215/75R14
Michelin
X (Mfg Spec)
26.8
1665
776
8.7
6
??
11.9
??
Michelin 1985
P215/75R14
Hankook
H724
NW
26.7
1664
778
98S
8.5
6
5.3
??
$81
Hankook 2014
P215/75R14
American Classic
NW
26.69
1664
98S
8.5
??
5.68
??
??
Coker 2014
P215/75R14
Toyo
Extensa A/S
Black
26.7
1664
778
98S
8.3
12.0
Toyo 2014
225/70R14
Hankook
H725
Black
26.3
1675
789
98T
8.9
6.5
6.6
??
??
Hankook 2014
225/70R14
General
Altimax RT43
Black
??
??
??
225/70R14
Cooper
Cobra GT
RWL
26.27
1675
8.92
6.5
7.2
??
??
??
225/70R14
BFG
RedLine
Red
26.3
1675
8.9
??
6.7
??
$186
Coker
??
SIZE
MFG
TYPE
Sidewall
OD
LOAD
RPM
LR
SWid
RimW
TWid
SLR
Cost
Source
8.50-14
BFG
Deluxe Silvertown (3-60 Mfg Spec)
28.3
7.86
5.5
4.73
13.07
??
1960 BFG
8.50-14
Firestone
Deluxe Champion (3-61 Mfg Spec)
28.4
1265
8.04
5.5
??
13
??
1961 Firestone
8.55-14
GoodYear
Power Cushion (Mfg Spec)
28.24
8.5
6
??
??
??
1967 Goodyear
8.55-14
General
Jet-Air II Rayon
28.26
8.54
6
??
12.81
??
General 1971
8.55-14
BFG
Deluxe Silvertown Coker
28.1
1740
8.35
??
4.75
??
??
Coker
215R14
Michelin
XWW (Mfg Spec)
27.4
1770
765
8.4
6
??
12.2
??
Michelin 1979
HR78-14
Michelin
XWW (Mfg Spec)
27.5
1770
759
8.9
6
??
12
??
Michelin 1979
H78-14
General
Belted Jumbo 780 (OE)
27.85
8.8
6
??
12.65
??
General 1971
H78-14
coker
coker
WW
27.6
1770
8.86
??
5.75
??
??
Coker
HR78-14
Phillips66
used
NW
27.45
8.75
6
6
??
C300
??
P225/75R14
Michelin
X (Mfg Spec)
27.6
1795
757
8.9
6
??
12.1
??
Michelin 1985
P225/75R14
Firestone
721 Steel Belted Radial
NW
27.35
9
6
6.15
12
??
Firestone 10-86
225/75R14
Cooper
TrendsetterSE
NW
27.05
1797
8.7
6
5.6
??
??
Cooper 2006
H70-14
GoodYear
Speedway WT (Mfg Spec)
27.78
764
9.1
6
6.81
??
??
1967 Goodyear
P235/70R14
Firestone
SS Radial
26.66
8.85
6.5
6.27
11.54
??
Firestone 10-86
??
SIZE
MFG
TYPE
Sidewall
OD
LOAD
RPM
LR
SWid
RimW
TWid
SLR
Cost
Source
9.00-14
BFG
DS (3-60 Mfg Spec)
28.8
8.25
6
4.93
13.26
??
1960 BFG
9.00-14
Firestone
DC (3-61 Mfg Spec)
29
1355
8.53
6
??
13.2
??
1961 Firestone
9.00-14
BFG
DS Coker
NW
28.68
8.8
??
4.8
??
$184
Coker
8.85-14
General
Jet-Air II Nygen
28.3
8.96
6
??
12.99
??
General 1971
8.85-14
BFG
DS Coker
NW
28.68
1860
8.8
??
4.8
??
??
Coker
J78-14
General
Dual S-90 Sidewinder
??
28.24
9
6
12.81
??
General 1971
J78-14
GoodYear
OE Polyglas
DW
28.2
??
67 NY
measured 67 NY
235/75R14
American Classic
NW
27.87
1930
104S
9.25
??
6.3
??
??
Coker 2014
245/70R14
generic
No known examples
27.6
1940
??
??
??
??
Edward Mills Antique Tractors 1930-1960 Antique Cars 1960-1985
On 6/25/2019 7:33 PM, 'Rich Barber' c300@xxxxxxx [Chrysler300] wrote:
??
From:Chrysler300@xxxxxxxxxxxxxxx<Chrysler300@xxxxxxxxxxxxxxx>On Behalf Of Curtis Roys curtisaroys@xxxxxxxxx [Chrysler300]
Sent: Tuesday, June 25, 2019 1:44 PM
To: Don Warnaar <300country@xxxxxxx>
Cc: Noel Hastalis <cpaviper@xxxxxxxxxxx>; Chrysler300ClubInternational <Chrysler300@xxxxxxxxxxxxxxx>
Subject: Re: [Chrysler300] American Classic radial tiresWell, that's an easy decision, my 65 300L is original from front to back & I was hoping to keep the wheels & hubcaps!!!
Amazingly after sitting for 25 years in a garage, it still has original bias ply tires.??
This club is AWESOME,??
Thanks,
Curtis
Curtis Roys, LLC
432-967-2582
--Ray Jones. Y'all come on down an see us. Ya hear?
__._,_.___
Posted by: Ray Jones <1970hurst@xxxxxxxxx>
To send a message to this group, send an email to:
Chrysler300@xxxxxxxxxxxxxxx
To unsubscribe from this group, send an email to bob@xxxxxxxxxxxxx or
go to https://groups.yahoo.com/neo/groups/all/manage/edit
For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm
For archives go to http://www.forwardlook.net/300-archive/search.htm#querylang
![]()
![Yahoo! Groups]()
Back to the Home of the Forward Look Network
Archive Sitemap