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Hey Charlie, Maybe if you had a 3.73 rear end like my stock '37 Master you could keep up with it! Seriously, I can't tell a great deal of difference between it and my '48 Fleetline with 15" tires. (not sure what ratio the '48 has)

The 15" wheels in 1948 is NOT an early/late thing. The 15" wheels with low pressure tires were an option. The low pressure tires were much fatter and were designed to improve riding quality. 24 pounds of air was all that was required.
the tires used by GM were the US Royal Air Ride, The Firestone Super Baloon and the Goodrich Low Pressure.
Engine RPM"s were almost the same.
All 1948 Plymouths had low pressure tires (Good Year Super Baloons).
1948 Fords used regular 6.00X16 tires. In 1949 and 1950 Ford still used a 16" tire with the 15" low pressure optional.
The 1948 Chevrolet Engineering Features shows the advantages of the low pressure tire.
The disadvantages were they wore out faster, squealed more in n, etc and steering was slightly harder for parking. Most owners inflated them to 26 or 28 pounds (cold)

A 1937 Master with the 3.73 will not sound any better at high speeds than the 1948 with the 4.11. This is due to the larger, noiser fan blade used with the factory 3.73 gears. The better insulation used in 1948 may have helped also.

I agree! I think the improved insulation etc. was a big factor in the sound and vibrations transmitted.

It's usually not a good thing to disagree with Gene, so I'm treading lightly here. :-) I had come to the conclusion that the 15" tires were a late '48 addition for a couple reasons. When I read the August-September 1948 Chevrolet Dealer News, it talks about the new 6.70-15 low pressure tires. I just always thought this was their introduction to the dealer network. My rationale was supported in my mind since I can't find any evidence in my April 15, 1948 Master Parts Catalog that 15" tires were an option yet. No speedometer gears for passenger cars with 15' wheels (Group 4.337). Only 16" wheels available for passenger cars (Group 5.803). Based on that, I jumped to the conclusion that late in the model year, they introduced the 15" tires...

Just looked at my 48 spec pack and it shows 16 x 4.00E and 15 x 5K. Don't know what the letters stand for. I heard the 15's were an option, but don't know when they would be an option. I have my original 16's in the garage. I bought a set of 15's for my 48.

1948 0ption list dated 2-1-48.
Tires with 15" wheels.
6.70x15 4 ply option #287A
6.70x15 6 ply 288A
6.70x15 white wall one side #290A

Page 21 of 1948 Engineering Features(published Jan of 1948.
Regular production options, first item
The selection of regular tire production options has been enlarges for 1948. Newly designed 6.70x15 4 and 6 ply tires may be obtained in conjuction with 15x5K wheels..............almost 1/2 page of description.

1948 production began in Feb. of 1948.

Thanks, Gene! As I said - usually not a good idea to disagree with you. :-)

When you have the first hand experience backed up with Chevrolet literature and take the time to consult both the advice is as close to 100% as humanly possible. Gene is truly a wealth of knowledge and VCCA asset. Proud to have him helping us all better understand Chevrolet history.

Yup.....Gene is the man.

Just remember, if you don't listen to what Gene has to say.........you're probably gonna make a mistake!!!!

Was there ever a point in 1948 production where 15" wheels became standard and not an option?

No....you could have the last 1948 made and if the dealer didn't check the 15" option box on the order it would have 16" wheels.
I would suspect early in the year the dealer didn't understand or know what the option was all about so just did't order the 15" wheels. Also the cheaper Stylemasters would be less apt to have the 15" as it added to the cost of the car.

Seems like a read somewhere that the Fleetline Series in 1948 came standard with 15" wheels. Now I will have to research where I saw that.

Dale - did you run the '48 up to 65 mph ?

We just had the discussion a few weeks ago. The 15" wheels were optional for all models.Just look at the beginning of this thread.

A '48 with 15" wheels will easily run 65 mph. and the engine is not that noisy at that speed.

Yep!

I have enjoyed all of the information relating to tire size for a 1948 Chevrolet. I learned a lot. I guess that the only thing left to do is for me to challenge Cousin Dale to drive 65 mph and try to keep up with me at the Six Cylinder Tour in New York. I will be the one in the Battleship Gray 40 Coupe driving 65 on the interstate.

dtm

I'll be the guy in the Oxford Maroon '48 driving 57 mph. :-)

Dale just put a tow rope between cousin Dave's and yours so you can follow at 65 mph. Will save a bunch of gas to boot.

I look a it this way. If the car can maintain 57 MPH whats few more miles per hour...and drive 65.