You can't really go by the sidewall, door sticker or charts you see on the internet. Its takes a combination of test to TRULY find the right PSI based on needs and expereince.I have a 2004 F250 6.0 crew cab lariat. The stock tire size is 265/75/16 and the door jamb says psi is 55 front, 70 rear. I have larger tires now which are 285/65/18. Should I keep the psi the same? And if I tow, what should I have psi set to?
This is great info. I will definitely be doing the chalk method. I really appreciate all your guys insight on this stuff. I always try to be safe and informed with my vehicles, especially when towing, so having this info is awesome. I kinda wondered if my math method was legit, but sounds like this chaulk method will give me a more definitive answer. Thanks again!!!The problem with the math method is you have no idea about the tire construction stiffness in the wall or in the tread, especially the difference from one tire model or brand to another.
The caulk method is a good DIY way. The pro way and WAYYYYYYY more expensive is to use FujiFilm Prescale. It's how I've seen it done while at the Transportation Research Center in OH, where NHTSA and many other companies test. I've also seen it done at a Smither's test track in Texas where Michelin and BFG were testing.
While "I am a need to know every aspect kind of guy" (ZMANN reference), I use chalk, too.
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