Why no mechanic will ever say" Im NOT SURE"

Generally for cars high 20s-low 30s PSI is a good rule of thumb. You never want to go to the max (50PSI) in this case. As you drive the car the PSI will increase as the tires warm up. Even more so in cold weather.

 

Except for our Mercedes which is 43 lbs as I recall and a whole host of other cars on the road. The rule of thumb garbage went out with wide white walls in the early 60's. Car design and tire technology has seen to it there is no more rule of thumb and is why in the EU the tire pressure is required to be posted on the windshield and in the US it is required to be posted in a prominant place.

Tire pressure problems are the number one cause of tire failure and a big cause of accidents yet I still personally find it shocking so few drivers have any idea what their inflation pressures are supposed to be or have any idea how to find out.

 

As to the original question you really should start shopping for quality and not price. Any professional I know who is not insecure about his abilities has no trouble admitting to not knowing specifications. That is why referance books and materials are printed. I will not allow my people to apply specifications from memory. I insist they are looked up to prevent mistakes. Even tire pressure.

 

Don't be sorry speed racer, it's all about "the show", right?

 

I have no trouble whatsoever admitting that I don't know everything and that my memory isn't perfect.

I frequently "look it up", from more than one source if possible.

 

I don't understand the tone of this thread. There is a lot of confusion about tire pressure and I think it's a topic worth discussing.

I just had new wheels and tires put on my Gallardo. I brought the car to a very well respected tire and alignment shop in the area. A couple of days after getting the car home, my son and I were about to go for a ride and I did the standard tire-pressure check and cold, they all were at the maximum pressure rated for the tires. I was amazed! Thinking the tire shop knew what they were doing, I checked the door jam, the owner's manual and a few on-line sites and its clear the tires were WAY over-inflated. I was amazed and realized these guys just don't work with exotics very often and the guy who mounted the tires just didn't know what to do.

Bottom line... it's up to us to know the basic specs for our cars. Most of us aren't mechanics, but tire pressure is pretty basic.

After doing a little research, I made a poster-size print out for all of my cars front/rear tire pressures and put on my garage wall so as I'm moving around my garage with my compressor and gauge, I need only glance at the poster to see what's right for that car and that tire.

Frank

 

Maybe the tire shops are setting the pressure to maximum, so YOU can then go and set the pressure to what you desire it to be...it's easy to LOWER the pressure from 50psi down to your desired pressure. But if they set it at 30psi, and you want 36psi...you gotta have an air pump to accomplish that...just a thought. Oh...and I personally believe that the pressure on the door jam is a good place to start...then adjust from there. The pressure on the sidewall is simply a "do not exceed" number...really has nothing to do with your specific car.

 

The maximum pressure shown on the sidewall of the tire is the pressure required for the tire to safely carry the maximum rated load of the tire.

Nothing else.

 

Blair- Sorry, could not resist. And yes, Husker was funny but would lead us all down the garden path while he was laughing at us.

What Brian says is very important because the tire pressures for Ferraris were developed by testing them until an optimum combination was found for each manufacturers' tires.

Some cars, like the 348 and 355, are very sensitive to tire pressures and the way they are set is sometimes counter-intuitive. Such as the car is oversteering, so you increase rear tire pressures only to have it oversteer worse.

It is, however, hard to believe there is anybody working at a tire shop who does not know the tire pressures (for OEM tires, at least), are on a sticker near the door opening.

Here is an example of what I mean about tire pressures, all for 355s with 225/40 18s F and 265/40 18s R:

Bridgestone F 36psi R 32psi
Michelin F 27psi R 31psi
Pirelli F 32psi R 29psi
Goodyear F 38psi R 33psi

All developed experimentally, for sure, and the handling can be pretty weird if the tires are very far off the recommended pressures.

Taz
Terry Phillips

 

Ferrari assigns an engineer to work with the respective tire companies to develop those numbers. They do extensive testing with every combination at Fiorano.

 

Blair- You are not listening. What brand of tires are you using? Hiro posted all the recommended tire pressures above, directly from the Owner's Manual. All Brian would do is look up the same numbers already posted.

Taz
Terry Phillips

 

Are you making these comments tongue in cheek or are really "That guy?"

 

On all of my Ferraris I just look on the glove box lid....

All of them say the same numbers, and the 308GTB DOES have a wierd stagger in pressures front vs. rear.....

If you miss it, the handling definately suffers....

 

Blair- Do not get defensive. No offense intended. The Hankooks are a whole new ball of wax and obviously not in the OM. You may have to do a little testing yourself, or Hankook may have recommended settings. If you try each of the settings in the handbook in a big parking lot, you will be able to see which settings feel the best to you. Some people like oversteer (loose) and some like understeer (push), although neutral will give you the best tire wear.

Taz
Terry Phillips

 

Q. Whats the difference between Push and Loose?


A. With Push you get to see the accident.

 

Brian- True. Hard to do a good job observing your own accident in a rear view mirror.

Also comes down to which you would rather test, the seat and headrest, or the airbag?

Taz
Terry Phillips

 

Greetings everyone.

Perhaps I can help to explain the tire settings chosen on this particular car, since I work at the shop were the alignment was done.
After speaking with the owner about how he drives the car and seeing the tires he chose to install in place of the original pirellis we were able to confidently select a pressure that would meet his needs. Since the car no longer rides on the original tires and the replacements are a different much "harder" tire with a higher max psi rating. We chose to exceed Ferrari's recommendation but not the tire manufacturers max rating. Since the car isnt a track car 40psi will give him a very compliant ride over bumps and still encourage agile handling for a colder tire.

Hope this clarifies the discussion, Please feel free to pick on me if I have confused anyone.
We do genuinely care about our choices and spend as much time listening to the owner as we do adjusting the car. Thanks!

 

I am getting the Hankook Ventus V12 Evo (summer tire) for my 360; I should probably look at a mix of tire manufacturer specs, F-car manual, and ride feel to adjust the tire pressure accordingly? Also, can anyone tell me how to find the age of the new tires via tire code? Thanks in advance.

 

I have said " I'm not sure" many times in my life but then I didn't give up until I had the correct answer.

Karl

 

aztar
Yes! do your homework. the earlier posting had air pressure recommendations of four different tire manufacturers and all were different. Not to mention none of us know how and where you drive.