Ok, just to reiterate what I’m both asking and have a beef about. If you were to do a google search for what pressure rating you should use in regards to your vehicle. You would get back many results most of them telling you to always go with the manufacturers recommendations.
So I understand that max PSI is actually max PSI as the tire is cold ( meaning the car is undriven or has not been for 3 hours). I also understand that if there is not a bias in the pressures of the tires from front tire inflation pressure vs rear tire inflation pressure that is listed by the manufacturers it could mean the difference between a sure stop and a fishtail in a panic situation.
My question is, how can you go by a manufacturer’s recommendation when you change the tires to a brand/ratio different from what the car came with and possibly having a completely different max PSI rating? Or if you otherwise modify your car to perform differently than OEM? The manufacturer can’t possibly know what your specific driving experience is like or what your needs are in cases like these.
So to finally ask, if the manufacturer’s is no longer reliable and the max PSI on the tire is not a great idea, how do you customize tire pressure for your particular situation?
If this level of accuracy is important enough, replace all four tires at the same time. If a slightly lower level of accuracyis acceptable, then make sure to replace the tire with one that has the same recommended PSI as the matching tire on the other side.
I will also attach this LINK I came across I’m guessing written by a police officer and is really only relevant to police cruiser style Crown Victorias. Still, I think the message in it is worth the read. Come to whatever verdict you will on the information.
Ask the guys at Tire Rack. They sponsor the tire and wheel forum at most car enthusiast message boards, and they’re happy to answer questions such as this.
That just seems wrong. On an '06 Camry V6, Toyota recommends 32psi and the tire manufacturer (Dunlop) simply lists a max of 44psi. Are you saying that if you replaced those tires with some other brand that had identical specs, you wouldn’t use 32psi?
If you use too low of a psi for the tire, you’ve got a serious danger of a blowout (see: Firestone on Explorers circa 2000). The car manufacture will specify a lower psi for a smoother ride. The closer you get to the max psi, the better gas mileage you’re going to get.
yes, my feelings also many, more studied than myself say that you will wear the tire out more on the center than on the sides at a higher inflation than what the car manufacturer recommends- which is exactly why I opened this topic here on straight dope, because I’m not getting the answers I need by searching.
Everyone assumes that the tires you get after the first 4 you get on your car are going to be matched with the manufacturer’s original choice, but this choice was partly made because the manufacturer called around to see what the best tire they could get for their car at the lowest bulk price to fit into the car’s budget. It’s a well know fact that manufacturer’s nearly never put the absolute best on their cars simply because it would fall into a different price bracket for potential consumer’s. Tires are no different. So when a part fails on my car I see an opportunity to buy something of better quality at probably a better price. Sometimes those circumstances lead to a tire that is not exactly like what came OEM on the car. Any change in your tires proportions or modification to the suspension system changes the rules that is specified on this wonderful tire info placard everyone refers me to.
My OP implied already that I’d done the research on the topic I just still don’t have my answer. I want to know how to adjust my tire pressure according to the characteristics of the tire I-I want or anyone could get… would there be a utility like this? PSI calculator or something? What gives? Why does everyone trust manufacturer’s so much? They don’t drive your cars.
Max PSI is the maximum pressure the tire can take regardless of what car it’s on. It’s never meant to be a recommended tire inflation value, and has nothing to do wit tire in your make/model car. The car manufacturers recommendation is going to be pretty close to accurate as long as the tires you choose are similar to the ones that came on the car.
The tire manufacturer has no clue what the total weight or weight distribution for your vehicle is, which is key in determining tire inflation values for proper contact patch areas.
:dubious::rolleyes:
This guy contradicts himself in that article.
My personal take on tire pressures is this.
The car maker knows the most about your vehicle. Read the owner’s manual, and tire pressure label in the car. If there is a optional tire pressure listed (sometimes shown for large loads or highway use) use that.
If there is only one set of pressures, note the pressure difference from front to rear. The start experimenting maintaining the listed pressure difference.
Example tire label is F 35 psi, R30 psi Try 40/35 and see if you like it. If that is too harsh, drop to 38/33. In no event go above the max pressure listed on the sidewall.
Sooner or later you will find a set of pressures that work for you
This is a frustrating and unsatisfying topic to research. I got interested a few months ago and wound up thinking the following:
The car manufacturer recommends a pressure which, though they don’t go into the details, is a compromise between various considerations including tire life, driving safety, fuel economy, and comfort and responsiveness of the driving “feel”.
You should be able to count on having no rude surprises if you buy replacement tires that are within the size ranges your car’s manual or manufacturer recommends, and fill those tires to the pressure the manual or manufacturer recommends.
There are more things that go wrong faster and with nastier results if you start lowering the pressure relative to the original pressure in the original tires or that same pressure in new tires per #2 above, than there are if you start raising the pressure likewise.
Relative to the manual’s recommended pressure, raising the pressure improves the mileage more and more the further you go, and at least for a while also makes the tire better able to resist damage and have a long wear life. Various things start getting worse at various rates. Perhaps most noticeable is the ride feeling a little noisier.
Lots of people treat the max pressure stamped on the tire as an upper limit, and experiment around in the range between this and the manual’s recommended pressure. The stories you read on discussion forums find various minor advantages to various points in this range. Nobody tells about catastrophic blowouts or other nightmares in this range.
Some people go well above this max pressure. A fellow whose specialty is stunt driving on just two tires, like a leaning motorcycle, uses something like 100 or 120 psi. Some police departments supposedly use high pressures in this neighborhood too.
There are so many major authorities that are scared of legal problems (which may be deserved or not) arising from making pressure recommendations that what one would expect to be the best authoritative info isn’t available.
My car (Citroen C4) recommends something like 35 psi front, 37 psi rear. This used to work relatively well with the stock tires (Michelin Exalto II), but after 20.000 km the tires started slipping very badly. Lowering the pressures did increase the available grip but compromised steering response a little.
After a while I changed the front tires with Continental SportContact3. I started again with the recommended pressure and the grip was quite good. Then I gradually tested the car with lower front pressures. I found that at about 30-32 psi at the front I got max grip. I kept the car with this pressure for about 5.000 km and then inspected the front tires. They were worn more at the center, an indication of overinflation! What the heck, I was already running them 4-5 psi lower than the recommended pressure. The problem was that I couldn’t lower the pressure anymore because then I got too much wear on the outside sidewall which indicates that a more negative camber setting at the front is needed. Unfortunately the car has McPherson struts at the front, so the camber angle is not adjustable without doing some serious mods first. Maybe if I could dial in some negative camber I could run the tires at higher pressure and at the same time increase the grip and get a more even tire wear.
I am planning to install a Bilstein PSS or KW Variant1 height adjustable suspension kit sometime in the future. Lowering the ride height on cars with McPherson struts has the side effect of making the camber angle more negative so maybe I will get the desired camber without custom top mounts or eccentric screws.