Midlife 814 Report post Posted February 6, 2020 Guys, it is amazing what so-called professional tire stores tell customers about proper tire pressure. I have a 80k 2010 car and the service manager immediately went to the door panel to see what the manufacturer recommended for tire pressure. WRONG! That's the pressure recommended for the tires provided with the car when sold new. Every tire model has its own unique profile/design and the tire pressure changes whenever that tire model goes onto various different vehicles. Tires recommend maximum tire pressure but that is NOT what the pressure should be. So...how do you determine optimum tire pressure? Start with the obvious: you want the tire to have maximum contact with the road and you do that by examining the tread contact with the pavement. Here's how I do it: a run a line of water in front of the tire and drive the car over the water far enough that the water left by the tire track is completely dry. Examine the water mark across the tread: when tire pressure is optimum, the water pattern when the track just reaches dry-ness should be equal across the entire tread. If the water drys first in the center and last at the edges, then the tire is underinflated. If the water pattern drys last in the center and first at the edge, then the tire is overinflated. Adjust tire pressure so that you have a consistent, even pattern. Do this for all four tires and the pressures should be fairly equal. You can average the four if they are not too far off. Some cars may have such a weight different from front to back that you may have to vary tire pressure front and back. I've been doing this for 20+ years after being told this by a former tire mechanic. Most tire stores have never heard of this and refuse to believe it. It works! 1 1 Mach1 Driver and RPM reacted to this Quote Share this post Link to post Share on other sites
Vicfreg 771 Report post Posted February 7, 2020 I have never used this water method. Sounds pretty cool. I typically use the door sill pressure as a guide, as it is tied to the load rating of the original equipment tires, especially in my truck when I am towing something. I will have to check into the water method with my local tire guru, we can compare notes..... Quote Share this post Link to post Share on other sites
aslanefe 333 Report post Posted February 8, 2020 On 2/5/2020 at 7:59 PM, Midlife said: Guys, it is amazing what so-called professional tire stores tell customers about proper tire pressure. I have a 80k 2010 car and the service manager immediately went to the door panel to see what the manufacturer recommended for tire pressure. WRONG! That's the pressure recommended for the tires provided with the car when sold new. Every tire model has its own unique profile/design and the tire pressure changes whenever that tire model goes onto various different vehicles. Tires recommend maximum tire pressure but that is NOT what the pressure should be. So...how do you determine optimum tire pressure? Start with the obvious: you want the tire to have maximum contact with the road and you do that by examining the tread contact with the pavement. Here's how I do it: a run a line of water in front of the tire and drive the car over the water far enough that the water left by the tire track is completely dry. Examine the water mark across the tread: when tire pressure is optimum, the water pattern when the track just reaches dry-ness should be equal across the entire tread. If the water drys first in the center and last at the edges, then the tire is underinflated. If the water pattern drys last in the center and first at the edge, then the tire is overinflated. Adjust tire pressure so that you have a consistent, even pattern. Do this for all four tires and the pressures should be fairly equal. You can average the four if they are not too far off. Some cars may have such a weight different from front to back that you may have to vary tire pressure front and back. I've been doing this for 20+ years after being told this by a former tire mechanic. Most tire stores have never heard of this and refuse to believe it. It works! Midlife, your method did not work for me, it has been 2 days and the black tracks are not drying up. Quote Share this post Link to post Share on other sites
Midlife 814 Report post Posted February 8, 2020 Ha! You need to do this at night, obviously, and during snowy weather. *G* Quote Share this post Link to post Share on other sites
smh00n 87 Report post Posted February 25, 2020 I run all my cars at 36-38 psi. My wife pulled 70,000km (40,000 miles?) out of a set of Bridgestone Potenza 18" on her daily drive. Most others struggle to get 40,000 km out of them. I got 120,000km out of a set of Goodyear cargo, which are a commercial 1 tonne tyre. Running them at 30psi or around that just wears them out. On my Hoon cars it doesn't matter what pressure I use, the rears don't last as long as the fronts. Quote Share this post Link to post Share on other sites
Vicfreg 771 Report post Posted February 29, 2020 smh00n "Hoon Cars...." ahhh Now I get the member name...… "hoon".... very clever For us Americans, we don't really have an equivalent name, although we do the same stuff. I had to reach out to "Wikepedia" to get an official "hoon" definition... I love this "politically correct" version... A hoon, in Australia and New Zealand, is a person who deliberately drives a vehicle in a reckless or dangerous manner, generally in order to provoke a reaction from onlookers. Hoon activities (or hooning) can include speeding, burnouts, doughnuts, or screeching tyres.[1] Those commonly identified as being involved in hooning are young and predominantly male drivers in the age range of 17 to 25 years.[2] Speeding?....burnouts?….screeching tyres?….. omg....what is this world coming to..... Cant' a man have a little fun now and then.... The cops are no fun. Or, I guess over there the "Constables" A famous English Blues Singer said it all.... funny story about the Constable trying to stop street musicians from playing the blues in London. So, whether it's the blues, or burnouts, I am all for the Hoons. Worth a short listen, great story and song. Look up the musician, and ever more fascinating story Don't try to Quote Share this post Link to post Share on other sites
smh00n 87 Report post Posted March 4, 2020 Well down here we are so restricted in what we can do to cars now it's annoying. Cops will pull you over for 5km/h (about 2mph) over the limit. We have speeding camera's everywhere. You spend more time watching the speedo than the road. A Hoon used to do all the Wikipedia stuff, now it's just someone in a ricer with a body kit and a 4" polished muffler. Although some of us keep the tradition alive: https://www.summernats.com.au/ Quote Share this post Link to post Share on other sites
Vicfreg 771 Report post Posted March 5, 2020 oh, that looks like a great show! Quote Share this post Link to post Share on other sites
Mike65 475 Report post Posted March 7, 2020 That is cool, but now back to our original discussion. I set the tire pressure on my Mustang & our 3 trucks around 32 PSI. Quote Share this post Link to post Share on other sites
Midlife 814 Report post Posted March 7, 2020 After reflection, my recommendation is for maximum friction between the tire and the road, which is surely desirable. Manufacturers have an incentive to maximize miles per gallon to satisfy CAFE requirements, so they are likely to boost tire pressure. Safety should be the primary concern, which is why maximizing tire friction to pavement is my recommendation. Quote Share this post Link to post Share on other sites
