Sorry guys, I think I have a silly one:

The door sticker in my car has completely faded away, hence I do not know what the tire pressures should be.

I have the optional alloy wheels (15 x 8) on which the factory fitment was 255/60 x 15; the pressure for this should be on the decal
However, my car is currently equipped with a slightly smaller tire:
245/60 x 15 but that should not differ too much.
The pressures are not given in the shop manual, nor in the owners manual, which both refer to the sticker
Anyone, please.
Thanks,
Cor

 

Expect someone to post 81 factory rec. nos. for most people.
I don't run the stock nos.!
28-32 PSI should do it, you could start w/ 30 & adjust up or down a little.

 

all cars are 30-32 give or take a little. been that way for decades..

 

I have Goodyear 255/R60-15's up front and 275/R60-15's rear. I asked my local Goodyear dealer what the proper tire pressure would be, suggesting ~26PSI. He never asked what wheel width I had...8.5". I was shocked when he said 38-40 psi!!! I think that is way too high but refrained from arguing with a man who should know his business. The MAX pressure as indicated on the sidewall is 44 psi.

 

Isn't the recommended PSI on the tire itself.....

 

All the tires I have seen have the maximum pressures listed. I always go by the sticker recommendation on the vehicle.

 

NO, there is normally a max. pressure.

69 Chevy
He doesn't know! Some truck guys run near or max. all the time. lol

 

Just looked at the door label of my '82 and the maximum PSI for the 255 60R15 tires are 35 PSI....Hope this helps-Pete


Edited post to reflect my '82 Tire pressure door label and to change recommended tire PSI to maximum PSI, now that I have been educated. Thanks, been getting it wrong all these years!

 

Cold..30 psi here

 

Well, varying responses, but also figures from the sticker, I asked for, thanks!

I currently have 2 bar in them #29 PSI, and thought this to be too much;
the reason is that I also own an Mercedes Benz of the same year ('81), which has smaller tires: 205/60 x 14, so a smaller width, as well as a smaller diameter,but the weight of that car is just the same.

The tire pressures given for the MB, with 3 persons an light baggage is 32 PSI front and 30 PSI rear, for speeds up to 120 MPH, over 120 MPH add 4 PSI.
Under 100 MPH reduce with 2 PSI.

So, with the same weight of car, and lower speeds, and bigger tires, one would expect much lower pressures. This should add to the comfort while cruising.

Never mind, you gave me what I asked for, so can't complain, can I???
If there is a specialist around here who would come up with calculated figures, I would love to hear!

Thanks all!
Cor

 

That's a common misconception on the tires- see if you can find a topic called something like Tire Test that I did.

The MB is probably heavier in front, C3s are about 50/50 wt. dist.

 

Well you got your answer and that is good!

The pressure listed on the side of a tire is for its rated load which may not be your cars load rateing. Now the OEM will adjust that for the weight distribution of a given car and for it's handling characteristics which will almost always be different than whats on the side wall. Watch the wear patterns on your tires and adjust along the way to get even tire wear, assuming you have a proper alignment and all is in good condition.

 

Early radial tires were rated at air pressures that were too low (24-27 psi). As a result, there were many tire failures do to sidewall flex and tire overheating in the mid-1970's. Immediately after this, the industry did a 'knee-jerk' reaction to putting too much pressure in them (over-correction) and specified 32-36 psi range.

In the long run, about 30-32 psi has become the accepted pressure level for 'normal' sized radial tires on C3's with street/highway use.

 

Not true for late model vehicles (especially low profile tires). For instance, the OEM recommendation for my 2009 passenger car is 35PSI.

 

The Owner's Manual for my 1974 specifies 20psi front and rear for GR-70/15 tires. Makes you wonder how thorough GM (or the tire manufacturers) were in their research and testing in that era.

 

I'm with ED79, 30 psi (cold)all around. I have 245/60/15 front & 255/60/15 rear. 71 vert w/bilstein(spl) shocks.

 

seriously? That is really really hard to believe.. Not a typo by you or them?? I am going to check my 68 owners manual just for yucks to see what they were recommending then...

I know in some cars lower pressure is recommended (26 - 28) simply to provided a more comfortable ride. Also, the maximum pressure is not necessarily the recommended pressure.

 

I've got a '76 running 255 x 60 x r15. The 1970's started introducing radials and when they started the factory recommended for many cars was 22-23 psi in the front. Another five or ten years went by and they figured out that was inadequate. Then they went the other way for a few years and, in my view, somewhat overinflated them for recommendations...run 35 psi which is the tire's max.

What I've found for my own use with these big wide tires with lots of grip which puts lots of forces on the sidewalls and the seal when pushing them that the answer for normal driving is somewhere in between. I run 30-31#'s cold for normal use, decent flat grip but not bad on milage either. when I took it to VIR's road racing track for a day in May their recommendation uniformly is that you run your tires 3-5#'s higher than your normal to make the sidewalls stiffer yet against the wheel rims due to the greater side forces with aggressive cornering. Some guys at the track actually used infared thermometers across the tread face after runs to check how the tire was responding and adjusted air pressure accordingly to get the best shape at the junction of tread and track surface. I found that 35#'s was good on the track though I'm not the most aggressive driver there and 30-31 is super for non track.

The shop once looked up the factory recommended when balancing my four and I didn't know it and they put 22#'s in the front and rear and when I got home and put it away in the garage the next time I backed out, stopped, ran the door down then went forward with a sharp right turn I scrubbed the left front tire right off the rim and it went instantly flat. Nothing wrong with the tire other than 22#'s was too little air. I'm not good enough to visually tell on these big, wide tires whether it has 22 or 32 pounds...a good air gauge was the only way at least for me. The big tires are sorta different creatures and if you were running 18" wheels and different aspect ratios I'd guess that was different again.

I think without specific expertise but being around when radials first started being used to now that it's a fair representation of what works and how and why the rec's changed at least on the cars I own.

Lance P.