Eldorado tire pressure

[LenInLA]

Question pls: the factory recommended settings for my 1976 Eldorado indicate 28 and 20 psi. My Bentley, which is approximately the same weight runs on 30/36 psi. Cadillac recommendations seem way off - or am I just not getting something?

Thanks!

[76eldo]

The car will feel good with 30-32 all the way around.

If it feels a little bumpy, adjust downward.

Brian

[Glen]

The Eldo is front wheel drive and has more weight on the front axle then the rear.   Therefore you need more pressure in the front.   The shop manual recommends front 25 psi and rear 22 psi for my 68 ELDO. 

[The Tassie Devil(le)]

The Factory Tyre Pressures for my '72 Eldo was for Cross-ply tyres, and to give a soft ride.

Radials require at least 35 on the front and 30 at the rear, simply because of the weight at the front.

Bruce.

[Roger Zimmermann]

My Bentley, which is approximately the same weight runs on 30/36 psi.

You don't say which year is your Bentley. As it was probably fitted with radial tires, the pressure is higher than for bias-ply for the same capacity. This is one of the main differences between bias-ply and radials tires. Then come driving habits: when Cadillac were delivered new in Europe, the tires had probably to be inflated at a higher pressure because Europeans and not driving like Americans...

[Jon S]

The Factory Tyre Pressures for my '72 Eldo was for Cross-ply tyres, and to give a soft ride.

Radials require at least 35 on the front and 30 at the rear, simply because of the weight at the front.

Bruce.

Agree - Could even go to 32 at the rear.

[TJ Hopland]

The 76 Eldo would have come stock with radials?   Interesting that it said 28 and 20.  20 seems especially low.   The back of those cars are not that light.

I run radials on my 73 and 30-32 all around is what I have been doing.  Higher just seem to really make for a harsh ride.

[savemy67]

Hello Len,

The factory recommended tire pressure is usually for the factory installed tires, or tires of the same type and dimension.   Comparing the Cadillac recommended pressure to the Bentley's recommended pressure is not a valid comparison.

What tires are on your Eldorado?  Most likely, somewhere on the tire sidewall is a UTQG (uniform tire quality grade) rating.  The rating provides an indication of the tire's treadwear, traction, and temperature resistance, so that any tire can be compared to any other tire made by the same, or another manufacturer.  Several tires that fit your Eldorado will come with different UTQG ratings and each tire will feel different at the same pressure, based on how the tire manufacturer built the tire to achieve the UTQG rating that the manufacturer desired for that tire.

The tire sidewall will also have the month and year when that tire was manufactured.  How old are the tires on your Eldorado?  Some people replace tires based on age, not mileage.  Given the job the front tires on an Eldorado have to do, the front tires need to be good quality.

You might want to research UTQG ratings and inquire as to which of the factors is most important for the feel you want in your Eldorado.  For example, a tire with a UTQG treadwear rating of 400 might feel harsher than the same size tire with a rating of 200 at the same tire pressure.  The tire with the 400 rating is supposed to last longer than the tire with a 200 rating, but other factors influence tread life.  The UTQG ratings are somewhat subjective, but you can use them as a stating point in tire selection.

Respectfully submitted,
Christopher Winter

[TJ Hopland]

These days we are lucky to find a 75 series tire at all and even luckier if its got any sort of a white wall.   We can only dream of having options to compare beyond that.    Maybe that would be an option if that service we have hard of from Diamond Back is true and reasonably priced where they can apply the white wall of your choice to the tire of your choice? 

[35-709]

Diamondback does, and will, indeed put the whitewall width of your choice on the tire of your choice.  I requested a 7/8" WW on these tires and that is exactly what I got.  Whether one considers it reasonably priced or not is up to that person.

The whitewalls on my '35 resto-mod seen in the picture below are 245/70-16 Michelin Latitude Tours with added whitewalls by Diamondback.  The invoice was $1167 (including their purchase of the tires and shipping) for the 4 tires, no doubt more today.  They are now 5 years and 23,000 miles old.  Most of the miles put on these tires are long distance turnpike miles at 70/72 MPH including 5 trips each summer since 2011 from Florida to upstate New York with side trips to the Boston GN, the Lake George GN, and Indianapolis to visit my great-grandson.  We do not trailer the car.  Point is, the tires perform as I would expect from Michelins and look as if Michelin itself had made the tires as whitewalls, which Michelin does not.   

[LenInLA]

The tires on my 76 Eldorado are the whitewall Uniroyals - 235/70-15. Look to have plenty of thread left, but I haven't checked the age. I suspect they're quite old. I could be wrong, but I believe these were the factory tires.

What do you think of the Coker tires? They go for about $200+ for white walls.

I had to shell out close to $3000 for four new Avon tires for my 1992 Bentley this year, so nothing shocks me anymore

[Jon S]

I have the Coker's and am very happy with them.  I like that they have the BF Goodrich logo on the blackwall unlike Diamondback's smooth no name buffed off blackwalls.

[James Landi]

Not intending to add to chorus of varying voices, but I have found that the factory recommendations make for a much more comfortable ride-  I suspect that the torsion bar suspension may contribute to the shock transfer when tires are inflated beyond the recommended pressure.  I have fitted my19 85 Eldorado Convertible with Vogue tires, and I run them at the 30 psi lower min pressure, and they provide a terrific ride WITHOUT the harshness associated with "standard radial " inflation.     I might also add that for around town driving, riding on "under inflated " tires will provide you with the comfort you expect and you won't do any noticeable damage to the tires.   I would not, however, take an under-inflated tire on the highway.     James

[Caddyjack]

The 76 Eldo would have come stock with radials?   Interesting that it said 28 and 20.  20 seems especially low.   

It must be a typo in the original post. The 1976 Eldo pressures as stated in the manual and on the sticker inside the glove box is 28 psi front, 24 psi rear.

That said, I run my '76 Eldo 32 front, 28 rear with great results.

[TJ Hopland]

I don't know if I have tried different front vs rear.   Next summer I may give it a try and see if there is a difference.

Interesting theory about the torsion bar suspension making things different.   Did the torsion bar Mopars have a different feel too?

[76eldo]

Those Uniroyals are too old to run safely at highway speeds.
I don't normally subscribe to the 10 year rule but you may be pushing 20 year old tires. I haven't seen those Uniroyals for a long time.

Brian

[EAM 17806]

I use 28 PSI on all fours on my 76 coupe deville, which weighs 5025 lbs, after many trials of various tire pressures. Higher pressures than 28 make the ride feel like you are in some kind of a truck, especially at 32 PSI you can feel every crack in the rode. The factory sticker suggests 24 front and 28 in the rear for radial tires with a full load in that year. Sure, there was a slight improvement in radial tire construction since then but not enough that would require higher pressures, in my opinion. A 28 PSI on all fours give you a decent ride and helps somewhat on gas mileage and sufficient pressure for safety. Some guys put high pressure to try to obtain better gas mileage and just don't care about the hard ride; these cars are used for enjoyment and if you're concerned about gas mileage primarily then these great cars are not for you.  EAM

[James Landi]

 It truly "boils" down to ride quality versus tire pressure-- with safety being the imperative. (IMO)  I don't think you're pushing the safety issue if you're driving at moderate speeds (around town) with the lower recommended pressure-- why sacrifice the Cadillac experience and have your car ride like a TRUCK?).   I can say for certain that the Vogue tires seem to shock absorb exceptionally well at higher inflation pressures with the torsion bar suspension ('85 Eldo).   I also feel that GM achieved the smooth ride by recommending those questionable tire pressures that, to our modern sensibilities seems dangerous.   Happy New Year, James

[Caddyjack]

I use 28 PSI on all fours on my 76 coupe deville, which weighs 5025 lbs, after many trials of various tire pressures. Higher pressures than 28 make the ride feel like you are in some kind of a truck, especially at 32 PSI you can feel every crack in the rode. The factory sticker suggests 24 front and 28 in the rear for radial tires with a full load in that year. Sure, there was a slight improvement in radial tire construction since then but not enough that would require higher pressures, in my opinion. A 28 PSI on all fours give you a decent ride and helps somewhat on gas mileage...

Keep in mind that the Eldorado is front wheel drive and all of that extra weight up front is the reason for increased pressure by 4 psi (as recommended by the factory) for the front tires. The Coupe DeVille would understandably be different.

[bcroe]

I actually run tires enough to wear them out before they are too old (6
years).  I adjust pressure so that they wear evenly across.  Worn on the
edges means too little pressure; in the center is too much.  The result
is some 10 psi higher than the "soft ride" recommendation.  Fine, it
handles better.  The local dealers can always get me the right size at
a reasonable price. 

There are only 2 car tire sizes here.  I have cars not driven so much, so
when the most frequently driven are showing wear, those tires are
transferred to a car not driven so much.  The tires off the car at the
bottom are recycled and the rims (blasted & painted if needed) go for
new tires, for the first car.  The process keeps relatively new tires on
every car, without buying tires for each one.  Bruce Roe