Best tires for a 47 Super Sedanet?

[Hans1965]

Hi all, I just acquired a very original 1947 Buick super Sedanet which needs new tires among a few other things. Manual transmission as this is one year before dynaflow was introduced. 

I was thinking back and forth on changing the rear end gear set. 

As these cars have a 4.45 rear end  a 3.90 would bring down rpm at a given speed. That is an option. 

 

I need to decide on tires, too. The smaller series cars had 16 inch wheels, while the Roadmaster had 15s. 

 

I tend to buy Firestone 650-16 tires, which is the standard size for this car, with 4 inch white walls. Maybe 700-16 are even better? Would they fit without rubbing? Or I try to find 15s and put 850 on them? 

 

Many options, but what would you do as you have much more experience than I have?

 

Thanks for advice! Highly appreciate that. 

 

Best, 

 

Hans 

[JohnD1956]

There are tire converter applications on-line which would tell you the circumference of your original tire.  I would try to stay as close to that measurement as I could for purposes of speedometer accuracy.  Do you already have another set of the 15" Buick rims on hand?  If not, don't forget that they have the extra holes in-between the lug bolt holes for the alignment pin.  But since there are more 16" tires sizes available than the 15" , I would also try to stay with the 16 inch rims and wheels.

[Hans1965]

John, thank you for the hint about the 15". I tend to stay with the 16" as I have no 15" anyway. Here I need to glue km/h figures onto the mph speedometer anyway which is required by law, so accuracy is not an issue.

 

I cannot figure out why the small series cars have 16 inch wheels and the Roadmaster 15 inch.

[60s GM Fan]

Firestone Bias Ply tires are fantastic.  I use them on my 55 and they're beautiful tires.

[Buicknutty]

 This depends on your preferences I think, but I run radial tires on my '41 Roadmaster, and really like the way they drive. The ones I have are called Diamondbacks, I don't know what is available where you are. These are wide white radials, and of course the look is slightly different.

 I have also changed the rear axle ratio from a stock 3.9 to a 3.4 out of a '55 Century, with a correcting unit on the speedo cable so that my speedometer is quite accurate.

 This is an upgrade I highly recommend if you want to drive the car at freeway speeds. Not easy to do, and finding the parts can be the toughest thing to do.

Keith

[JohnD1956]

3 hours ago, Buicknutty said:

 This depends on your preferences I think, but I run radial tires on my '41 Roadmaster, and really like the way they drive. The ones I have are called Diamondbacks, I don't know what is available where you are. These are wide white radials, and of course the look is slightly different.

 I have also changed the rear axle ratio from a stock 3.9 to a 3.4 out of a '55 Century, with a correcting unit on the speedo cable so that my speedometer is quite accurate.

 This is an upgrade I highly recommend if you want to drive the car at freeway speeds. Not easy to do, and finding the parts can be the toughest thing to do.

Keith

Here is a question for you Keith. My friends 1950 Special was outfitted with radial tires and it was very difficult to steer when moving slowly like when backing into a parking space. He asked me to park it once because of this and I was surprised that it was as difficult as he said. I thought it was the tires myself but i don't know that for certain.  I did ride in the car when it was being test driven by our friendly mechanic and don't recall any problem like this on the open road but he did have to wrench it at an intersection. Do you find it hard to steer like that?

[Buicknutty]

 I don't find the weight objectionable, though that is such a relative turn it's difficult to quantify. The very little bit I drove my '41 with the old bias ply tires the steering effort seems to be the same, or similar with the Diamondbacks.

 However, my son's '55 with standard steering is much easier to turn, and even moving very slightly it feels almost as easy as the '56 Roadie with power steering.

 Somewhere in my memory I remember something about the steering ratio being changed to a higher numerically ratio, so it would be slower, but have less effort. Though we have not had the chance to drive the '55 much it seems to bear this out. My thoughts are this was done early 50's, but otherwise I just don't know.

Interesting, as in this era they would have wanted to sell power steering, but also it would have made it easier for women. My Lady is a good example. The 41 is very difficult for her to drive, but the '55 is a lot more feasible.

So, after all this rambling, I cannot give you a definite answer!

[Hans1965]

I have Firestone 820-15 tires on both my 49s and they are really hard to steer at very low speeds but I love the looks. The 760-15 on my 52 Pontiac Catalina are easy, the same on my 52 Buick Riviera. To move my 53 Buick with 225 radials that has standard power steering is really hard work when the engine is not running. That was the main reason for me not to buy radials for my non power steering cars. You get used so quickly to the characteristics of bias ply tires. The "lose" front end and a lot of play in the steering wheel are much more frightening to me . 😩

 

 

[60s GM Fan]

Loose front end has more to do with your suspension components.  When was the last time they were adjusted/serviced?  I know that with my 1937 LaSalle she'd do okay at speeds up to 45 mph but one time when I took her up to 65 mph there was a very high pucker factor coming from yours truly.

[60FlatTop]

You can narrow down steering problems by dropping the drag link from the pitman arm. With the steering box isolated you can check it for play caused by wear and look at the pitman arm ball. It is supposed to be round. If it is oval the looseness at that point can vary with the position in its swing.

With the drag link still disconnected you can pop the outer tie rod ends. That will allow you to wiggle the center link and inner tie rods to check for wear or stiffness. Each wheel will now be isolated to swing through its steering arch tight or loose king pins or ball joints can be inspected. I once saw a set of king pins on a Ford truck that were so tight it broke the bearing plate out of the steering box and the worm gear rode up and down the sector making it look like the truck had telescoping steering.

Even with the springs installed you can still use a bar to check the control arm pivot points.

A thorough inspection like that can be done in a couple of hours and only consume three cotter pins, pretty good investment of time and materials.

 

If you find a warn and replaceable part it is not too hard to find a MOOG number through an Ebay search. Depending on your urgency, mine is never really high, you can run a search with notification for the part number. There are some deals from sellers who don't know the applications. A couple of years ago I assembled a full set of MOOG rebuild parts for a '48 Packard front end for about $200. Its kind of a "save while you pucker just a little" plan. Big puckering, just buy the parts fast!

[Brooklyn Beer]

All I know is I put radials on a couple cars over the traditional slightly taller and narrow original size tire and I went from easy non power assist steering (50 Chrysler) to trying to dock the Queen Mary against a stiff wind.  I will be going back to the original spec tire