1938 Special Tire Size

[Guest searle1965@gmail.com]

Anyone know what the tallest 15" whitewall tire available is ? Can't afford an overdrive right now so looking for all the help I can get from the tires. Previous owner put on a new set of very low profile tires so anything will be an improvement.

 

    Thanks

 

 

.   Tyler

[jvelde]

1938 Specials had 16" diameter wheels, so may want to verify what you have!

[LAS VEGAS DAVE]

I RUN  7/50 R16  on my 38 even though I have an overdrive. They fill the wheel wells better that is the main reason I bought them. Mine are Coker Radials that look like BIAS PLY tires. They have the WIDE white walls.

[Guest searle1965@gmail.com]

They are 15" wheels so it looks like I'm going with 750-15 Lester white walls, they're about 30" in diameter which is about 4" bigger than what is on it now. That should give me a little less rpm's. Make sense ?

[MCHinson]

If you have correct era Buick 15 inch wheels, you might want to consider selling them and buying the correct 16 inch wheels. You could probably easily do some horsetrading with someone with a Century. The Centurys were produced in much smaller numbers and those Century 15 inch wheels are harder to find.

 

The sidemount spares on my 1937 Century are 16 inch wheels instead of the correct 15 inch ones. I would certainly be potentially interested in a swap to get the correct spare wheels for my Century. 

 

The correct 16 inch wheels are much more common. you could probably buy a set of them cheaply and make a good profit selling the 15 inch wheels to someone with a Century if they are the correct era Buick 15 inch wheels.  

[MrEarl]

53 minutes ago, MCHinson said:

If you have correct era Buick 15 inch wheels, you might want to consider selling them and buying the correct 16 inch wheels. You could probably easily do some horsetrading with someone with a Century. The Centurys were produced in much smaller numbers and those Century 15 inch wheels are harder to find.

 

The sidemount spares on my 1937 Century are 16 inch wheels instead of the correct 15 inch ones. I would certainly be potentially interested in a swap to get the correct spare wheels for my Century. 

 

The correct 16 inch wheels are much more common. you could probably buy a set of them cheaply and make a good profit selling the 15 inch wheels to someone with a Century if they are the correct era Buick 15 inch wheels.  

 

Simply put, I think Matthew would like to do some horse tradin with you sir. 

[MCHinson]

I would not be opposed but I did let him know that his wheels, if original era wheels, would be worth more than the 16 inch ones. Looking a bit closer, the 1937 15 inch wheel is not the same part number as the 1938 15 inch wheel. The 1938 and 1939 15 inch wheel is the same part number. 

 

I will also be picking up a 1938 Century project car in the near future. I have no idea what wheels it has, so even if his wheels are 1938 Century wheels, I would certainly be interested.

[Guest searle1965@gmail.com]

So how would I tell if I have correct '38 Century wheels. I can probably post a picture tomorrow some time, car show tonight, parade tomorrow .

[MCHinson]

The only way that I know of would be to either find a part number on one somewhere or else comparing it to a known example.  

 

This old link might help you do the comparison. I am assuming that the wheel identified as a 1939 Century wheel is, in fact, correctly identified. The 1938 Century wheel and 1939 Century wheel are both listed in the chasis parts manual as Part number 1303946. The 1937 Century wheel is listed as Part number 12999010. I have no idea what the difference is between the two but suspect that they would be interchangable.

 

 

[Guest searle1965@gmail.com]

These are the rims that are on my '38 Buick.  The first picture is a rear rim, the second picture is the front.  They are different because they take different hubcaps.  Previous owner said it was like this when he bought it.  

[MCHinson]

I am not the expert but I think that those are a little bit later wheels.  

[jenz38]

I've switched over from the 6.50 x16 7.50x16 (only on rear axle,also i like the look ;)..on my lowered car) years ago .., because of the higher ratio..

My Car runs now, with the same Engine revs ,5 miles faster...

With bigger tires as these 7.50, are its not longer possible to change a wheel with air in the tire, too less Space between fender and axle..

 

 

[suchan]

Not absolutely sure, but I think the bolt pattern on a 15 inch '38 Century rim isn't the same as the 16 inch rim used on a Special. Those definitely look like later rims. If you're investing in new tires (not cheap), you should consider getting 16 inch rims first. Bigger tires will lower rpm's. Your motor must be screaming at 55 mph with low profile tires.

Jenz, cool car!

[DonMicheletti]

On the '38's the Special and Century wheel center and bolt pattern are the same. The Roadmaster is different

[37_Roadmaster_C]

On Friday, June 30, 2017 at 8:50 AM, MrEarl said:

 

Simply put, I think Matthew would like to do some horse tradin with you sir. 

 

I agree with Lamar....  But he has a Buick, why would he want a horse?  (yea I know, but I could not resist).

[Guest searle1965@gmail.com]

I can get tires that are 30" in diameter for 15" rims, about the same as the 16" tires. What would I be gaining by going with 16" rims?

Besides that , my rims are already finished. Thanks for the advise, everyone.

[mcdarrunt]

My 37 Special had 15" wheels with clips to retain hub cap, probably had been changed but look like they are period correct. It also had the 4.44 rear axle so I put 8.25x15 tires on it which REALLY filled the wheel opening and had to raise car by the frame to remove wheel. Still was not a left lane cruiser so I went to an open rear with a 2.73 gear and 27" radial tires which look too small. 2100rpm is 63mph now so it suits our needs for long distant cruising---about 8000 miles per year. From my trials and lots of errors I think a 28-30" tire would be best. I know some say 3000rpm is acceptable but I would try for near 2500 at 65mph if highway driving is on the agenda. Higher rpm OK for town driving or short cruises.

[jenz38]

5 hours ago, mcdarrunt said:

My 37 Special had 15" wheels with clips to retain hub cap, probably had been changed but look like they are period correct. It also had the 4.44 rear axle so I put 8.25x15 tires on it which REALLY filled the wheel opening and had to raise car by the frame to remove wheel. Still was not a left lane cruiser so I went to an open rear with a 2.73 gear and 27" radial tires which look too small. 2100rpm is 63mph now so it suits our needs for long distant cruising---about 8000 miles per year. From my trials and lots of errors I think a 28-30" tire would be best. I know some say 3000rpm is acceptable but I would try for near 2500 at 65mph if highway driving is on the agenda. Higher rpm OK for town driving or short cruises.

 Do you have pics from your new (wich kind?) rear axle installed in your car ?

Another Tranny with adapter also ?

 

Your fix sounds much interesting...

 

Thats my dream :   a T5 overdrive Box..

(...yes guys.. i know about the big "rat-tail", to do that on a torque tubed car with only a panhard link on a coil springed rear axle..?..)

 

[mcdarrunt]

I made all my adapters since we have the machines to do so and none were available then but now there is Bengstens Adapters in Minnesota that offers a bolt in kit for a Buick Straight 8 to a GM bolt pattern bell housing. The open rear end is from under a 1970 El Camino (Chevelle) and which had all the coil spring and torque arm mounts cut off, ground, and leaf spring perches welded back onto the axle tubes. This rear end was exactly the right width. My 37 leaf springs have shackles on both ends so had to make trailing arms to keep rear end in position.  I see your avatar shows a 38 which has coil springs which might make the job even easier. I only tied the lift up for three days, start to finish, so it's not a hard project. Some pics for grins:

 

Photo 1  Buick bell housing is near the same physical size as a modern GM

Photo 2 Three inch driveshaft tube fit main bearing bore perfectly

Photo 3 Spool on main shaft retainer bore to exactly center the bell housing

The usual jumping through hoops to get the starter/flex plate the correct spacing, dowl pins located, and starter located. notice the mock up is done with wood and the final is with aluminum plate.

[LAS VEGAS DAVE]

Seems the easiest way to get a nice cruising gear is to install overdrive.

[suchan]

On 7/6/2017 at 5:27 PM, searle1965@gmail.com said:

I can get tires that are 30" in diameter for 15" rims, about the same as the 16" tires. What would I be gaining by going with 16" rims?

Besides that , my rims are already finished. Thanks for the advise, everyone.

It's a matter of how much non-originality you're comfortable with. Do you plan to put '38 hubcaps on the wheels? Will your current wheels hold those caps? Do you plan to pinstripe the wheels, as original? The wheels you show look like they take a cap that covers most of the wheel inside the trim riings. If no on both counts, then you might as well "run what you brung".