Tires

[Wm Steed]

The object of my earlier postings to this topic was not to start a debate on the mathematic equations that pertain to the tread size, etc.. It was to point out to the readers the importance of the overall diameter of tires and the importance of making sure that the wheel/rim is correct for the size of tire being mounted to it. 

Most late model SUV's do in fact have 16" tires, however, they also have wheels that are in the 7"- 8" wide range. If one of the current P size 16" tires are mounted on the early Ford, Plymouth, GM 4.5"/5" wheels  the tire will not have good road contact and the rim/wheel could fail as a result of excessive stress....Bill

[Andy Wylie]

It could be surmised that the larger the number, or the greater the alphabetical letter, the larger the tire, however when you get in into the P-metric sizes, the equation can change. A P235R75 is a large tire, yet a 235R60 is not as tall but it is much wider.

Bill the first number is the tread width and the second a percentage of that representing the sidewall height ...235 x .75 = 176.25mm
I went to 225/75 15s because 16in radials were scarce but there seems to be a lot of new SUVs and commercials using them now, Those big steels are fairly weighty. Plymouths are a 4 1/2in bolt circle, the other common one is 4 3/4.

[Wm Steed]

More info than you really wanted, or might need about tires.

Once I started looking into the tire size issue, it prompted me to look at other tires and wheels I have 'in stock'. I think that very few of us have ever taken the time to really compare tire sizes. I found some variations that I found to be very interesting.

As all of us know, the 600x16 tire was standard issue in the mid 1930's through early 1940's for the mainstream cars, Chevy, Ford and Plymouth. Larger cars used 650x16 or larger. The 1950's became the era of the 15" tire, 670x15 and 710x15, 820x15, then in the '70's everything switched to the 'G & H' size tire, ie, G78x15/ H78x15.

So..... what did all this switching of tires size denomination mean? Nothing really, except that the buyer had better beware of just what they were buying. It turns out that the 600x16 tire is a very large tire by modern standards. I always thought the 710x15 was a large tire because it was used on the larger cars, yet when measured, I found that on the average a 710x15 is 28". The H78x15 is also 28", where-as the G78x15 is 26.5". It could be surmised that the larger the number, or the greater the alphabetical letter, the larger the tire, however when you get in into the P-metric sizes, the equation can change. A P235R75 is a large tire, yet a 235R60 is not as tall but it is much wider.

If you are going to replace the tires/wheels on your car with 15", keep in mind that the overall size of the the tire is the most important part , especially when you factor in performance and safety....Bill

[brucepine]

I have 15" x 5 1/2" standard 1960s-1970s Chrysler products wheels on my 38 Plymouth.  No problem. 

[elmo]

I have just been out in to my workshop to recheck a measure my spare wheels again just to make sure before i open my mouth. Like Bill i have a colection of Mopar wheels,mine  ranging from  35,Plymouth 37, Plymouth , 39, Dodge,DeSoto&Plymouth,54&56Plymouth,  all of these have the same bolt pattern. one i haven't got is a 38 Plymouth as mentioned by Jim B ,were these an oddball.

[bobbyg]

  I have G-78X15 tires on my 48 P-15,the tire size is Ok,but I also have whats known as
Chrysler safety wheels I put on the front,I find that they are a little too wide,they let my tire on
a hard turn rub on the tie rod end.when I switched back to 670x15 on regular Plymouth wheels
they did not hit.They do not rub hard as to ruin the tire but they do rub.I found the safety rims
do not go good on Plymouth.also on the back they are too close too my skirts.

[Wm Steed]

The size of the wheel has no bearing on how accurate the odometer will be. The overall size of the tire mounted on the wheel is the governing factor. As I have already stated.... the average 600x16 is 27.5" so if you want your odometer to be correct you have to use a tire that is close to that size.

As Jim pointed out, not all wheels in the Chrysler line of vehicles are interchangeable, this is also true in the GM line, Buick, Olds and Pontiac generally won't fit a Chevy. I do believe though that when you get into the early fifties, Chrysler standardize the bolt patterns on their vehicles. A 15x5 wheel should not present any problems on any of the fat fendered cars, so long as the wheel did not come off of a disk brake car. The disk brake wheels generally have a different back-set which can interfere with the suspension on cars with drum brakes.  I found this out the hard way.

Before I started to write my responses to this topic, I looked through my collection of tires and wheels. I have a large selection of tires/wheels because of all the old cars I buy and sell, many times when we go to pick up a car it has been sitting for some time so I have to put wheels on the car to make it roll....Bill 

[elmo]

i dont know about a 38 desoto , but i have a 39 desoto and i have interchanged wheels from various years of both plymouth and dodge from 35 up to 56 and they all had the same bolt pattern, although the earlier ones were narrower. one thing you have to be aware of is if you go to 15" your speedo will not read true

[Jim Benjaminson]

Not sure what year wheels you are talking about in using Chrysler or DeSoto rims because they are wider but you had better verify the wheels will fit your bolt pattern.  For example - the 6:00x16" wheel on a '38 DeSoto has a different bolt pattern than that of a '38 Plymouth.  Found that out the hard way when I needed to replace a wheel/tire on my '38 DeSoto and thought I would use one from a Plymouth!

[Wm Steed]

Tires and wheels are without a doubt one of the most misunderstood components on a vehicle. Topics on the various car forums pertaining to the subject keep cropping up, with the question of whether radials can be used on my... '36 Jack Rabbit' ... being asked time after time.

During the mid to late 1930's and early '40 the average size of tire used on the Chevy's, Fords and Dodge/Plymouths was a 600x16 on a 4" rim. In some cases the rim size was increased to 4.5". The larger cars usually had wider rims, 5" or wider with tires ranging in size up to 700x16 and in some cases 15" wheels were used as early as 1936. In 1949 most of the manufactures changed to 15x5 wheels with the most common size tire being the 670x15, the larger cars usually had 710x15 tires. In many cases the 15" wheels used on the larger cars will be 15x6 and/or 15x6.5.

Generally, a 600x16 tire will measure 27.5" x 6" wide when mounted on a standard 4"/4.5" wheel of the 1930's/40's.
Generally, a P22575R15 tire will measure 27.5" x 8.5" on a 6.5" wheel.
Generally, a P23575R15 tire will measure 28.5" x 9" on a 7.0" wheel.

So.... what does all this number mumbo jumbo mean? When you read the numbers you should note that the 600x16 tire on a 4"/4.5" wheel will be 6" wide after mounting and inflation. The same relationship between wheel size and tire size holds true on the radials, 8.5" after mounting on a 6.5" wheel. Problems start to arise when you mount radials on early narrow wheels. The tire wants to inflate to it's designed size , however, the narrow rim pinches the tire in at the bead thereby causing the tire to have less than full contact with the road.

The 15' wheels used on the '49 and later Chrysler/Desoto should be in the 6'-6.5" range. The '49 + wheels should be a direct replacement for the earlier 16" wheels. In many cases you will find them with the spring clips for the hub caps. If someone tries to sell you wheels without the spring clips pass on them unless the mounting pads are there, you can add the clips if the wheels have the mounting pads. .

The P22575R15 would be the best match to a 600x16 for overall size, however, the width might  present problems....Bill

[Carmen]

Bill

That is some story and that is what I don't want to happen to me. That's why I am asking all of these questions. While my car will not be an everyday driver it will be driven as much as possible.

You said that if I got larger rims I can get larger tires. Will those rims from the  Chrysler or Desoto bolt right on? What year and model will I need? I like the idea of having larger tires only because in my mind the car will ride better. So if I understand you - if I get larger rims I need P205-75R15 or P225-75R15 tires? But if I stick with the stock rims I need ???

Thanks

Carmen

[Wm Steed]

Carmen,... i would not worry to much about looking foolish about tires when talking to a tire salesman, most of them don't know their rear end from a hole in the ground.
I recently purchased a set of tires for my '91 Ford pickup. I told the sales person that the truck was a hiway truck, not used off road. I was more interested in carrying capacity and good tire mileage. I checked the prices in three stores, all three recommended the same tires because the brand was made in USA. The prices varied by almost $300. Naturally I went with the lower price. The tires were installed and I drove away. Later in the day I had a need to go about ten miles east of town so I got up on the freeway. As my speed approached  45 mph I noticed some tire noise, by the time I got up to 70 the tires were making so much noise I could not hear the radio.

I went back to the tire store, they were closed so I had to wait until Monday. Upon telling the store manager my problem, I was informed that  the tires were now used (45 miles)  so he could not, or would not take them back. After much heated discussion between the two of us, I left to contemplate my next move. I went to my computer and looked up the tire company that made the tires. When I found the style of tire I had, there in black and white the tire description stated that the tires sold me were designed for 60% off road use in Australia and South America. The description also stated that the tires were only rated as FAIR on wet roads.

I printed the tire information and beat feet for the tire store........... I got new tires, which they had to order,  with a 100% credit for the first set.

You have not really clarified just what your intentions are with the use of your car:
If you are going to show the car, with minimal driving, stay with the 600x16 tires. Black walls would be more correct for a '41 because not many people purchased white side walls in '41.

As I have already stated.... If you intend to drive your car a lot, especially on the hiway, go for radials. The only problem with the radials is that the availability and selection of 16" radials is pretty limited. Your stock 16" wheels are a little narrow for most radials. If you upgrade your wheels to 15", preferably from a Chrysler or Desoto, the wheels will be wider, (6") they will also be "safety rims" made for tubeless  and you can use your stock hubcaps. With a 15 x 6 rim you can use P205-75R15 or P225-75R15. The P205's are close to the size of the old 670's and the P225 is close to the old 710x15.  I have P225-75R15 on my '53 Pontiac....Bill

[Carmen]

Ok guys. IS there such a thing as a wider tire? To me the tires seem small compare to the size of the car. The tire numbers are what I am looking for so that when I walk into my local tire shop they don't look at me as if I am from outer-space. Plus it makes it seems that I know what I am talking about - which I don't.


Carmen

[David Pollock]

The 41 Plymouth came with a 6:00 x 16 tire.
You could fit it with a 6:50 X 16 , but there is no real advantage in doing so.  Don't be lured into buying 6:50 x 16 truck tires  which are still available at many tire outlets. Your car will ride like a truck.
Whitewalls are a matter of personal taste, but very few 41s were originally equipped with them

Jim Benjaminson offers a complete line of Goodyear tires for your car. I have a set on my 35 Plymouth and they have run 14000 miles now with hardly any noticeable wear.  I highly recommend them...(and jim too)

[Wm Steed]

Carmen,.... as already stated by others, if you intend to show your car stay with the original type of tire.  However, if you intend to drive your car switch to radials.... P205R16 might be a little small if you have stock gearing and no overdrive... I have P205R65-15 on my '39 Plym conv, my gear ratio is 3.23 with an OD. At 65/70 mph I am pulling 2,1/2,200 rpm's , which is perfect for hiway cruseing.

If you do go to radials, make sure your front end is as close to perfect as it can be made. You will also have to have the alignment corrected for radials and you might want to install a steering dampener which will attach to the tie-rod and frame.

I have been running radials on all my old cars since the early 1970's. I would not want to drive a car with bias ply tires any further than the tire store to get them removed....Bill

[Go Fleiter]

Dear Carmen,

  beeing in holydays in Tuscany (no Plymouth conv. this time with me, as I travel with my 84 Years old parents)I have no access to my list of dealers: but www.CokerTire.com has a wide selection. I bought from Union Tires, Kentucky or one of the states around, but couldn't find it now on the www.Nice selection and nice prize than.

   Greetings from Siena, Italy! Go

[elmo]

Carmen are you going to show your car or just use it to drive and enjoy ,if show, use the cross ply tyres thatmvair reccomends , but for driving and enjoying i would fit 205R16" radials you will find your car much easier to drive. unlike crossplys they dont follow every bump and uneven piece of road. if it was my car i would choose whitewalls for whatever  type of tyre you decide on,they were available on Plymouths in 41

[mvair]

The original tires were 6.00 x 16 Goodyear. I got mine from Jim Benjaminson. They are still made by a company under license from Goodyear. I believe it is Kelsey Tire (www.kelseytire.com).

[Carmen]

Can someone please tell me what size tire I need for my 1941 Plymouth? Since I know NOTHING about tire size please tell me the numbers and/or letters I need to ask the dealer for. Also what would be the largest size tire I can put on my car?? Should I get white walls or black?

Thanks


Carmen