If you know that then why are you using the TIRE MANUFACTURERS specs for tire pressure? You may not use the same tire in different applications, but auto manufacturers do. My 84 GMC S-15 pickup came with the exact same tires (including size) as my Brother-In-laws 85 F-150 pickup. It’s done all the time.
It’s about being optimal. Too much pressure will give you less control because the tire will have less road contact. They’ll also wear out sooner then expected…mainly in the center. Too little pressure will again give you less control, worse gas mileage, harder to steer.
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I wonder if Jim has actually read what it says on the tire. I just went out and read the sidewall of the tires on my truck and my car. Truck has tires that are a well known, quality, domestic brand. Car has tires that are a well known, quality, pacific-rim brand.
Both state follow the pressures on the placard or owners manual.
Though Jim and I, as others on this forum, appear to be in the same age group. I suspect some of his ideas come from the days when car manufacturers often used very low price, two-ply, bias ply tires on their new cars. Not uncommon for owner to upgrade their tires soon after purchase. Remember seeing advertisements for “new car take-offs”, tires were sold very cheap.
Even then the manufacturer’s specified tire pressure with caveats for high speed and load conditions.
One car that had critical but often ignored tire pressure requirements was the Corvair. Failure to follow the specifications created severe handling issues.
CapriRacer is the most knowledgeable tire person on this site.
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Yes, actually, I have read the sidewall. The Corvair IS critical. Most Detroit iron from that era was not, but it is a good reminder. I still have a lot of factory codes memorized. I realize some of my ideas seem out of date, and maybe they are. I am opinionated. I am often wrong. I grew up in the fifties and am very retro. I am willing to admit I am wrong here. When was fifteen there probably were still 2 ply tires, most tires were 78 aspect ratio, Firestone was just about t0 release the bias pelted 500 Wide Oval tires (70 aspect ratio), and Mechlin was just then becoming known in America with 78 or 70 aspect steel belted radials with floppy (well, very flexible) sidewalls. So yes, I have seen a broad spectrum of tire history. I realize this is not the place for a throw back like me. I am likely to drive an old pickup, modify the suspension, and put larger tires on it, buy a 1964 Ford Falcon (or some other small compact) and switch the 6 for a V8. If I do, I still call old friends from the tire company. I may buy a new car and get the largest aspect wheel available and switch out the OE tires (which was or free cheap when I worked for the tire company and was strongly encouraged if not one of their tires–no c[eting brands in the parking lot). I am strongly biased against OE tires (better though they are), depending on who makes them, and in general I don’t buy OE as replacement tires. Sometimes door codes, sometimes not so much, sometimes they just aren’t there.
I agree that capri seems to be VERY knowledgeable on tires, as are others here as well. Others not so much. I also don’t quite have a handle on the editing option and my typing has degraded with age. I am very OCD, which was great help getting my PhD and helps with some jobs I have had, but it makes me rigid in thinking. I appreciate those who have been patient with me in correcting me on this issue. Others, not so much. I really do have a strong background in tires. Some changes I have seen have been somewhat affectations with limited actual engineering values, some had been widely accepted but almost appear in hindsight to have been a bust.
I originally dropped in her to affirm my decision to throw ought a very pristine not quite 20 yr old Continental spare I had (OCD act not to waste anything). I appreciate the reassurance. I seems unlikely I will be a regular here, so sorry for being nuusiance and take care.
Yeah, I remember. While that was occurring in the news, for some reason one local Ford dealership decided to run a full page newspaper advert, with a huge photo of an Explorer proudly displaying boldly lettered Firestone tires. The ill-timed advert became sort of the joke of the week at business water coolers and among newspaper columnists.
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