Correct tire size / aspect ratio for '67 LeSabre?

Hi,

would like to order some cool "Magnum 500" rims with tires. Problem is the car has 225/75R15 tires on it, but the registration says 225/70R15. So the correct aspect ratio is somewhat unclear.

The original drivers guide has the following info:

8.45 x 15, optionally 8.85 x 15

8.85 would match my 225 (millimetres) tire width, but it does not state the needed aspect ratio.

Any hints welcome!

Cheers,
Harry
 
To the best of my recollection, the low profile tire was pretty new in '67 and was only offered in a 70 series red stripe, usually "Polyglass". So your tire would have been a "full profile" tire and today most people use a 78 series to replace them.
I am sure there is someone who remembers more than I do:)
 
The P225/75R-15 is about 28.3 inches tall. The P235/70R-15 is about 27.95 inches tall. You could use either one and Final drive and speedometer calibration would be fine. You can't compare old car bias ply aspect ratio to new P metric. The important thing is overall tire height.
 
I had a 67 Electra and put the 225-75-15's on it. It used the 8.85's with no other tire option. These cars came with tires that were flat and linear, in line with the width of the rims. The problem I had with the Electra was the skirt brackets in the rear. The swelled beyond the rim radials didn't fit past them so I had to completely deflate the tires to remove the wheels. If you don't have rear skirts you won't have that problem. Another issue these cars have is narrow rear wheelwells. These cars are not tolerate of wider rims without modification.
 
Hi,

would like to order some cool "Magnum 500" rims with tires. Problem is the car has 225/75R15 tires on it, but the registration says 225/70R15. So the correct aspect ratio is somewhat unclear.

The original drivers guide has the following info:

8.45 x 15, optionally 8.85 x 15

8.85 would match my 225 (millimetres) tire width, but it does not state the needed aspect ratio.

Any hints welcome!

Cheers,
Harry
It depends on the width of the rims that you have, if you have the 6” wide rim, the factory size would have been 205/70/SR15 If you have the 7” wide rims they would have been 225/65/SR15
 
Ok, thanks for all the info!

In the meantime I remembered actually having a nice old 8.45-15 "diagonal" spare wheel sitting in the trunk of the leSabre, which is having around 70,5cm (27,76 inches) outer diameter. Now the currently mounted 225/75R15 wheels gave me approx the same diameter, so I guess 225/70R15 won't be a better option at all.

Then I found out that my registration papers have some kind of addon which states its also allowed to mount 225/75R15 - so thats definately the way to go.

All I need to check now is if the "Magnum 500" wheels have a similar offset/ backspacing than the stock wheels.

Cheers,
Harry
 
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Either one would work. On our '73 LeSabre we run 225/75/15 but a 70-series would look fine as well.

As for "correct", I can't say - but in reality either one would be fine.

Some pros and cons to consider (which, admittedly are probably barely noticeable on all fronts), the 75-series will:
- Have slightly lower RPM on the highway
- Have more airflow underneath the vehicle (which is generally a decrease in MPG because of more aerodynamic drag)
- Have slightly worse off-the-line launch (assuming infinite traction)
- Have slightly better pothole-smashing resistance
- Have slightly higher load rating, although check each tire's load rating if you plan on towing
- Show slightly lower miles on your odometer (fewer revolutions per mile)
- Be more inclined to be a "truck" tire since there are fewer cars requiring this size than there used to be
- Have the car sit slightly higher which is a matter of visual appeal & personal taste
... and so on. At the end of the day, the visual appearance would be the deciding factor for me.

BTW if you live in New England, I'm happy to mount & balance for free for you! Tires are a hobby for me and I have all the equipment and a few decades of experience to boot.

-Bob C.
 
All I need to check now is if the "Magnum 500" wheels have a similar offset than the stock wheels.

Cheers,
Harry
Those Magnum 500 wheels probably come in a number of widths, back spacing, and offsets. Offset and back spacing are NOT the same. You need to look and see what the specifications are for the EXACT wheels that you want to buy. It is easy enough to take an original wheel off your car and measure it's back spacing and width. Then you can look for other wheels that will fit.
 
Hi all,

still trying to gather the needed data to compare the "Magnum 500" aftermarket rims with the factory ones.
So far I was just able to find out the original rims should be size 15 x 5,5, but no data concerning their offset/backspace.

Does anyone know/have these numbers? Are they maybe stamped to the backside of the rims - like on current/modern ones?

The potential problem I see here is that the back wheelhouses of the LeSabre are pretty narrow...

Cheers,
Harry
 
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The potential problem I see here is that the back wheelhouses of the LeSabre are pretty narrow...

Cheers,
Harry

Harry hate to say I told you so but...I told you so! See post #4

I honestly believe a 7" wide rim would have to be custom backspaced and even then it's pushing the envelope. A 7" wide tread is going to be a challenge because of how narrow it gets as you go up.
 
Hi all,

still trying to gather the needed data to compare the "Magnum 500" aftermarket rims with the factory ones.
So far I was just able to find out the original rims should be size 15 x 5,5, but no data concerning their offset/backspace.

Does anyone know/have these numbers? Are they maybe stamped to the backside of the rims - like on current/modern ones?

The potential problem I see here is that the back wheelhouses of the LeSabre are pretty narrow...

Cheers,
Harry

All you have to do is take off one stock wheel and measure the back space. It will take you longer to remove the wheel than to measure. Offset can be calculated from back space, but it is not necessary. You can then calculate what back space you will need on a wider wheel to keep the wheel centered as stock.
 
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