Rim width

[Terry Lange]

I am in the process of shopping for new bias ply tires for my Comet Olds. I will either purchase them from Coker or Lester. This Comet was built on the basic Dynamic 88 chassis (stretched 24"). The standard tires on this model (according to the sticker in the glove box) is 8:50X14, with 9:00X14 being "optional." The more deluxe Olds Super 88 and 98 models had 9:00X14 as the standard tire, with a 9:50X14 as optional.

In order to get the highest load rating possible, I would like to get the 9:50 tire. Does anyone know if this tire would fit on the existing factory rims, which would have held either a 8:50 or 9:00 tire, or will I have to get a wider rim to mount a 9:50?

The Coker BF Goodrich 9:00X14 is rated at 1860 lbs @32 PSI, and their 9:50 is at 2000 lbs. Surprisingly, the Lester 9:50 is rated at 2130 lbs @36 PSI. The Lester is also $18 cheaper per tire. Both have the correct sized whitewall for 1959.

Terry

 

[Paul Steinberg]

Strange the way that things happen.. I just looked this up for a friend yesterday for his 1962 Chevy, which came standard with 7.50 x 14 tires on a 5.6" rim. The optional tire was the 8.00 x 14 tire, and it came on a 6.0" rim. Then I looked at the other factory service manuals that I have, and found that the 1963 Chrysler came with a 8.00 x 14 on a 5.5" rim, and the optional tire was the 8.50 on the 6.0" rim, and a note that "Brake drum distortion will occur if a smaller size wheel is used."

I did a little more digging, and came up with the following chart... The first numer is the size, the one below that is the diameter, and the next one is the cross section of the tread.

7.00-14
26.50
7.00​

7.50-14
27.30
7.40​

7.75-14
26.70
7.75​

8.00-14
27.60
8.10​

8.25-14
25.80
8.05​

8.50-14
28.10
8.35​

9.00-14
28.70
8.80​

I also realize that even though you say that your 1959 Comet was built on the basic Dynamic 88 chassis, we don't know for certain exactly what Oldsmobile supplied for beefed up components on the chassis, knowing that it was going to be modified. It might have some of the components that were used on the 98 series cars. Only close inspection will reveal if this is a possibility, and you would have to know what components changed between models. Now, having said that, if you check the data plate, and find that your car started life as a specific model that was sourced from the dealers inventory, then it will not have any beefed up components.
When you remove a tire from the rim, you will find the original manufacturers code marks in the center section on the inside of the rim. This will give you the size of the rim, and there will be a letter designation also. Then I would contact The Tire and Rim Association, Inc. and ask them to look it up in their yearbook for the recommended tire sized that the rim will support.

 

[Terry Lange]

Paul, thank-you for your research and valuable information. The car has been at a Packard mechanic for the past couple of weeks getting all the important stuff looked after, so it will start, run, stop and turn, although it was doing all 4 of these things before I took it in. In fact, I drove it the 35 miles to his shop (on surface streets).

My recollection is that the GM data plate indicated that this car was a stock Dynamic 88, so it was probably dealer purchased as opposed to being supplied by the Oldsmobile Division directly to Comet Coach. I had raised this exact question in a separate thread a couple of weeks ago, but it appears from the lack of responses that no one has this information as to when Oldsmobile started offering modified chassis specifically for the coach building profession. Even if this was the case, where on the data plate would this information be found?

Once I get the car back, I will have the spare tire popped off the rim and get the numbers that you referred to.

Thanks again!

Terry

 

[Paul Steinberg]

The data plate is located under the hood and is riveted to the cowl. It might be on the top horizontal side of the cowl, or it could be on the vertical surface of the cowl. They are almost always on the drivers (left) side. I have seen them mounted high on the vertical wall, and as in the case of my 1962 Chevrolet, it is mounted very low on the vertical wall. Here is a generic picture of what it will look like. Once you find it, please post a picture of it, and I will decode it for you.

This thread might be of interest.. It explains the relationship between C/B and Oldsmobile. Makes for interesting reading..

 

[John ED Renstrom]

now I though we answered your question. I remember is as being that comet never got partial cars from GM. that practice did not start till they move to Ark after the brake up of Comet and the start up of CB then the merger with Wayne corp.
but run the car over the scale. find out what it weights first. then decide on the tires. 2000 lb load rating tire will only give you a 8000 lb gvw.
the car will weigh any were from 5 to 6000 lb set up for 6 people at 200 lb each and then equipment at say 1000 lb. some time you get lucky and you have a original spare. that will let you know the size comet put on and the load rating. it really a eye opener to see the rating at what psi on the older bias tires.

 

[Terry Lange]

now I though we answered your question. I remember is as being that comet never got partial cars from GM. that practice did not start till they move to Ark after the brake up of Comet and the start up of CB then the merger with Wayne corp.

You're absolutely right, Ed. Keith Snyder pointed this out in a different thread, that Oldsmobile only started supplying chassis directly to C/B after they were taken over by Wayne Corp. My brain must have been stuck in second gear when I read his post, as that point apparently did not sink in at the time.

Regarding the Comet Oldsmobiles, if they were generally ordered through the same local Olds dealership with the knowledge that they were going to be converted for funeral or ambulance use, one would think that they would have been ordered with the widest rims and tires available on that model.

The previous funeral home owner of this car put five Toyo 800 Ultra Premium Touring P205/75R14's on it. They are rated at 1532 lbs., but clearly are too small for this Olds. Because he also replaced the spare with one of these bicycle tires, I still don't know what was originally on the car.

Paul, I do know where the data plate is on this Olds, as I had taken the information off of it to determine that the car was a Dynamic 88. Are you saying that any factory upgrade on wheel width would be noted on this plate?

Terry

 

[Paul Steinberg]

It is difficult to say what will or will not be noted on the data plate. Different divisions, and different manufacturing facilities used different standards as to the information that was put onto the data plate. As an example, if the car was ordered with heavy duty suspension, it might be noted, and research would need to be done to know what that option might include for upgraded parts. Sometimes having a copy of the original factory service manual, along with a copy of the dealership parts books will reveal much information, such as number of turns in the spring to identify the rating of the spring, or the different spring wire diameter for a particular model. If you have the parts books to look up the springs, it is possible to learn what the spring rate is from this number. I have an account with a spring manufacturer that has made replacement springs for the Cadillac Commercial Chassis cars, and sometimes they can make the spring from the part number, since they have the original drawings from GM, and other times, they don't. In that case, the original spring needs to be sent to their facility to have the engineering department analyze it to properly reproduce it. If the car has the original factory shock absorbers on it, you might be able to get a part number off of it, which will help in the discovery process. Does the car have coil springs or leaf springs in the rear? This also will help to establish a base line. You will need to learn more about the options that were available in 1959 before you will be able to decipher a lot of the history of your car. It took me over a year to just learn the facts about how my 1963 Chrysler was equipped, and I am still learning about it. Through the years, things get changed from original, and a lot of originality is lot. It is up to us, the caretakers of these fine vehicles to learn about them, and to diligently work to get them back to as close to original as possible, if that is what we desire. It is in your hands as to how far you are willing to go with this particular vehicle. Sometimes, a car is too far gone from original to be put back, and it is best to preserve what is left by updating that which cannot be replaced. This is where the modify / restore to original decision usually starts.

 

[John ED Renstrom]

from the way I understand it. they would build on a car you supplied ar if you requested one they had a locale dealer that they would drop down and get one from. now back in those days you could get anything for a GM dealer. so they could have ordered different springs and wheels and put them on the car during the build. the bigger 14 inch tires are getting vary hard to come by

1/2 inch in wheel width really will not show all that much in the the tire. if all 5 of your wheels are the same. they will have a stamped number on the face. then I would suspect they are the wheels that came from comet. they may or may not be the ones GM put on the car. but if comet changed them it would only be to a heaver wheel. me I would pick the tire with the largest load rating and not look back. here is a pictures of the gm stamp on one of the wheels off the 72. yours will have a different but similar number. this number is how gm ides there wheels. so if all yours have the same number they are all the same type wheel.