[harveyshepherd]

My new Mach1/PP came with Michelin Cup 2 tires which are just not compatible with daily driving. I bit the bullet and swapped them out for Michelin Pilot Sport 4S tires. The door frame says 33 psi cold however these are different tires. I just checked the cold pressure and my tire joint has set them at 35 psi. Which number should I use?

 

[Braindead]

What a great car. Believe my Boss is 35PSI front and rear staggered sizes. It’s my door label stated pressures. Air can expand maybe 5-6# on hot day. Actually might list on tire itself- small lettering. My spare says right on tire inflate to 60PSI. Have also seen a maximum recommended inflate numbers??

Just fill with 34#, can’t go wrong. Tire air will deplete with cold weather until driven which warms them up, need to consider that also. Fill with nitrogen, green valve cap and forget variables just recommended + or - pressures.

 

[07redstang]

Nitrogen is a waste of money for a street car. Just check your pressures periodically and with seasonal temp changes.

 

[ONEZ ST]

2 psi above placard pressure isn't anything to worry about but if you fell more comfortable with pressure set to the placard recommendation, go ahead and adjust it.

And there are some folks who will check the tire footprint using the chalk method and adjust tire pressure accordingly.

I tend to set pressure on the low side and save my kidneys from getting bounced around.

 

[Braindead]

And it gets worse. No, never used N2 either, wonder if you fill up spare too if you have one (don‘t answer). From time to time do see those give away green caps though. Years back went to own compressor and gas station type fill nozzle. Need for small sand blaster and filling balls, rafts, mattresses etc.

Here we go… along with air pressures, letting air out of rears for 1/4 mile stuff, still a controversy on tire rotation itself. Now I still “X” mine but only to change weight allowances and the Maine roads are all ”too muched” crowned. If going just from front to rear am still on high crown of road, never issue “Xing”. Jury’s still out on this one and a new Mach I ^^^, not certain myself??

Corvette had directional rims no less, veined brake cooling vented idea, brilliant!! Learning and maybe thought change coming up? Added; The overall design followed the “form follows function” theory of design. For instance, the front fender humps were toned down considerably from the C3 Shark design to improve forward visibility. Nearly every aspect of the car was designed this way. The aluminum alloy wheels had several very unique design features. The wheels were designed to have a right and left side, such that as the wheels turned, the vanes around the center hub button, functioned as exhaust fans to pull in air from inside the wheel wells to cool the disc brakes.

 

[harveyshepherd]

Thanks for the comments. The setup is staggered so that eliminates any rotation concerns. I'm just thinking with these ultra-wide tires (305s in front and 315s in rear) tire pressure might be extra important with regard to tire wear - or not?

 

[Braindead]

Yes, middle of tires common for pre-wear, too much air. Left to right of coarse for rotation, had our Buick in mind.

 

[JBert]

.... I'm just thinking with these ultra-wide tires (305s in front and 315s in rear) tire pressure might be extra important with regard to tire wear - or not?

maybe, maybe not much more important than narrower tires ... I'm thinking 33-35 should be fine, you could check the wear across the width of the tire after some miles to see if they are wearing evenly

...Corvette had directional rims no less, veined brake cooling vented idea, brilliant!! Learning and maybe thought change coming up?

I always thought that sounded like a good idea -- use the spokes like vanes to pull air through and cool the brakes .... I wonder if it actually worked and if so why aren't more wheels designed like that?

 

[Cobrajet67]

My new Mach1/PP came with Michelin Cup 2 tires which are just not compatible with daily driving. I bit the bullet and swapped them out for Michelin Pilot Sport 4S tires. The door frame says 33 psi cold however these are different tires. I just checked the cold pressure and my tire joint has set them at 35 psi. Which number should I use?

What about them isn't compatible with daily driving?
Also, what does it say the max is on the tire sidewall?
I always base the pressure that I run by what's on the tire. The car manufacturer states the tire pressure on the door jamb for what tires were installed on the car at the factory and also usually for ride comfort. Each tire manufacturer makes their tires a little differently and has differing max inflation pressures. The tires themselves will state a maximum pressure but it's unwise to go all the way up to that unless carrying a heavy load. Doing so will usually result with more wear in the center of the tread and will impact handling.
I usually go about 10-15% lower than the stated maximum on the sidewall. I tend to get even tire wear that way while still getting decent MPG. On my Mustang's Goodyear summer tires they list 37psi max so I have them at 32psi IIRC which is closer to 10% under max and is just about what the recommended psi is. On my other daily driver I think they list 50psi max so I have them at about 44psi.
If I leave the Ford recommended 35psi in my 50psi max tires then I get noticeably worse gas mileage and they wear on the outer edges of the tires. This was the same general result with my F150s.
Tire pressure should always be measured when the tires are cool. Adjusting the pressure for winter and summer is also important since lower temps lower the pressure.

 

[harveyshepherd]

When it comes to mileage I claim blind ignorance. I bought the car(s) to have fun and I do so I never look. The incompatibility with daily driving centers around the tramlining (wandering) and the inability to safely drive when the streets are wet. However if you want to lean into a corner the Cup 2 tires were freaking unbelievable.

 

[my89foxbody]

My new Mach1/PP came with Michelin Cup 2 tires which are just not compatible with daily driving. I bit the bullet and swapped them out for Michelin Pilot Sport 4S tires. The door frame says 33 psi cold however these are different tires. I just checked the cold pressure and my tire joint has set them at 35 psi. Which number should I use?

Use the number on the door jamb, that number is what Ford recommends for best feel and gas mileage. It doesn't matter the tire brand that you chose to install on the car

What about them isn't compatible with daily driving?
Also, what does it say the max is on the tire sidewall?
I always base the pressure that I run by what's on the tire. The car manufacturer states the tire pressure on the door jamb for what tires were installed on the car at the factory and also usually for ride comfort. Each tire manufacturer makes their tires a little differently and has differing max inflation pressures. The tires themselves will state a maximum pressure but it's unwise to go all the way up to that unless carrying a heavy load. Doing so will usually result with more wear in the center of the tread and will impact handling.
I usually go about 10-15% lower than the stated maximum on the sidewall. I tend to get even tire wear that way while still getting decent MPG. On my Mustang's Goodyear summer tires they list 37psi max so I have them at 32psi IIRC which is closer to 10% under max and is just about what the recommended psi is. On my other daily driver I think they list 50psi max so I have them at about 44psi.
If I leave the Ford recommended 35psi in my 50psi max tires then I get noticeably worse gas mileage and they wear on the outer edges of the tires. This was the same general result with my F150s.
Tire pressure should always be measured when the tires are cool. Adjusting the pressure for winter and summer is also important since lower temps lower the pressure.

Max inflation is for Max load, meaning if you were to load up the car with a bunch of weight the tires will hold X amount of weight at X pressure MAX. Nobody should daily a car with the tires inflated to MAX, it would be the worst ride ever. It would feel like the Flintstone car with concrete tires

 

[Cobrajet67]

When it comes to mileage I claim blind ignorance. I bought the car(s) to have fun and I do so I never look. The incompatibility with daily driving centers around the tramlining (wandering) and the inability to safely drive when the streets are wet. However if you want to lean into a corner the Cup 2 tires were freaking unbelievable.

I didn't expect mileage to come into the equation with your car. However, in the same sentence I also mentioned tire wear and pressure which is what you asked about. My 2014 GT was bought strictly for fun and so gas costs don't come into play with that car either though tire wear certainly does as they're not cheap tires. You bought the most expensive model under the Shelby that you can buy... mostly meant to be at the track which of course is why you're having these multiple problems trying to regularly drive a factory track car on the street.
In my experience inflating to the recommended pressure on the door jamb usually equates to a slightly underinflated tire wear pattern over time. At least that's what I've noticed on my past few daily driver vehicles where I've been paying attention. You've now mothballed the $500+ each street legal track tires that were a main feature of what the car was built and intended for with the Mach 1 Handling Package.

best feel and gas mileage

Feel, yes but mileage, no. Even so, he's not concerned with MPG or even feel for that matter since his car will have the stiffest suspension of any Mustang with the exception of maybe the Shelby.

Max inflation is for Max load, meaning if you were to load up the car with a bunch of weight the tires will hold X amount of weight at X pressure MAX. Nobody should daily a car with the tires inflated to MAX, it would be the worst ride ever. It would feel like the Flintstone car with concrete tires

Yes, agreed. That's what I said in my previous post.

The tires themselves will state a maximum pressure but it's unwise to go all the way up to that unless carrying a heavy load.
I usually go about 10-15% lower than the stated maximum on the sidewall. I tend to get even tire wear that way

I don't like spending $ on tires any more than I do on gas so this strategy has served me well over the last few years.
A tire with a max psi of 50 and a tire with a max psi of 35 were clearly designed and made differently. Therefore, I adjust the pressure accordingly to what my past results have shown me. Some people prefer more comfort and some prefer max tread longevity so I recommend to adjust as you see fit within reason.

 

[harveyshepherd]

When all is said and done I love the car. Yes I've had to make a few adjustments but since this is my last fun car I don't really care. Now if I can just stay away from the radar gun. Thanks for the comments.

 

[JBert]

the only time I know that "max inflation" pressure comes in to play, is when you are trying to load your F350 to the full GVWR

 

[johnnybeerotten]

This ain’t NASCAR. You’re not likely to be able to tell the difference between the 32 PSI on the door and 1 or 2 pounds extra. I would stick with 32 PSI.

 

[07redstang]

This ain’t NASCAR. You’re not likely to be able to tell the difference between the 32 PSI on the door and 1 or 2 pounds extra. I would stick with 32 PSI.

1-2#'s is probably on the conservative side of the gauge error factor.

 

[Braindead]

I also can see if those tires are like the P-Zeros (wear out very quick) something more temperature friendly is required. The idea of a purported track car used everyday to me is kinda a selling feature? Won’t last though any longer as say a GT driven everyday someplace. Should be put up for in-climate weather.

Had a friend that had a friend with a Mach way back. Trying to climb hill back up to main road in blizzard. Not doing well… had trunk full of loose sand and shovel in trunk. Just shoveled some under his wheels, WHAT! This was brand new car, not much longer out there as such.

This entire thing so far over 2#’s of air 🙈

 

[my89foxbody]

I didn't expect mileage to come into the equation with your car. However, in the same sentence I also mentioned tire wear and pressure which is what you asked about. My 2014 GT was bought strictly for fun and so gas costs don't come into play with that car either though tire wear certainly does as they're not cheap tires. You bought the most expensive model under the Shelby that you can buy... mostly meant to be at the track which of course is why you're having these multiple problems trying to regularly drive a factory track car on the street.
In my experience inflating to the recommended pressure on the door jamb usually equates to a slightly underinflated tire wear pattern over time. At least that's what I've noticed on my past few daily driver vehicles where I've been paying attention. You've now mothballed the $500+ each street legal track tires that were a main feature of what the car was built and intended for with the Mach 1 Handling Package.

Feel, yes but mileage, no. Even so, he's not concerned with MPG or even feel for that matter since his car will have the stiffest suspension of any Mustang with the exception of maybe the Shelby.

Yes, agreed. That's what I said in my previous post.

I don't like spending $ on tires any more than I do on gas so this strategy has served me well over the last few years.
A tire with a max psi of 50 and a tire with a max psi of 35 were clearly designed and made differently. Therefore, I adjust the pressure accordingly to what my past results have shown me. Some people prefer more comfort and some prefer max tread longevity so I recommend to adjust as you see fit within reason.

The best feel and mileage was in reference to the door jamb sticker that the auto maker recommends for the vehicle. I understood that mileage wasn't an issue for the original post, just stating a fact about the door jamb. I do a fair amount of high speed highway driving and if I had added more air to my tires I would be wearing the center of my tires due to expansion

 

[Cobrajet67]

the only time I know that "max inflation" pressure comes in to play, is when you are trying to load your F350 to the full GVWR

Actually, any extra weight comes into play and the tire pressure is supposed to go up the heavier you are from the standard no matter what the vehicle. However, the question then becomes going from what standard weight as a baseline do you start adding pressure especially when compared to other weight passenger cars.
The Inadequate Tire Pressure Sticker (motortrend.com)
Here's a hypothetical. I have a 2022 Charger R/T weighing 4286lbs and a 2022 Mustang GT at 3730lbs both with the same brand/size/type tires on them. If both say 35psi on the door the issue is the Charger weighs over a 1/4 ton more than the Mustang. Well, one of these cars will not have the ideal pressure for both tire wear and/or handling. I could go even more extreme in weight differences with the same tire as an example but I think that you get the point. About 35psi seems to be the general average recommended tire pressure by the manufacturer no matter if the car is 3000lbs or 4000lbs. That being the case it just doesn't make any practical or mathematical sense whatsoever to have 35psi in the same tires for both lighter and heavier cars.

As I said the recommendation has a lot to do with comfort but not as with much with tire wear. Comfort is even mentioned as a tire pressure variable in the owner's manual. The tire and car manufacturers won't mind one bit if you go thru tires a little bit sooner than you could otherwise get out of them.
Read the Motor Trend article above and you'll understand that trusting the door jamb tag isn't so simple or wise. You can put the door tag recommendation in your tires if you like. That's what the manufacturers want you to do.

The best feel and mileage was in reference to the door jamb sticker that the auto maker recommends for the vehicle. I understood that mileage wasn't an issue for the original post, just stating a fact about the door jamb. I do a fair amount of high speed highway driving and if I had added more air to my tires I would be wearing the center of my tires due to expansion

I understood that you were referencing the manufacturers recommended pressure on the door jamb tag when you said the best feel and MPG. That's why I agreed with you on the feel but definitely not MPG.
Probably 3/4 of my driving is highway and if I only run 35psi then the outer edges of my tires tend to wear out. This is why on my daily I have been running 10-15% under the max load on the tire and above the recommended door jamb tag for many years now. I get more even tire wear that way.

 

[johnnybeerotten]

1-2#'s is probably on the conservative side of the gauge error factor.

In my car I find the variance between the sensors and my Blue-Point electronic gauge to be very small, we’re talking tenths of a pound. In any event, I only use the dash as a relative reading, not an absolute, and rely on the Blue-Point for checking and setting pressures.