Car tire pressure gurus

[ramonesfreak]

This is a head scratcher

The door sticker says front 41 psi rear 35 psi

But, the owners manual for same size says front 48 psi rear 41 psi

That’s a big difference

Any idea why this would be?

[Steve Carlton]

My understanding is the door sticker is the best recommendation. Maybe the manual was giving you maximum pressure for when it's heavily loaded. The ride quality will be better at the lower pressure, obviously.

[p911dad]

What vehicle are we referring to?

[ramonesfreak]

2024 mini cooper John Cooper works 3 door


Both the door plate and manual say pressure are for 4 occupants.

There is a separate page in manual for over 100 mph driving but I’m not looking at that

[Steve Carlton]

I'd call MINI customer service, but I'll bet it's the lower set. I've seen corrected door stickers issued before, so you never know.

[ramonesfreak]

Here’s what I’m talking about…sorry iPhone wouldn’t let me rotate the sideways photo

Maybe the door card is specific to OEM tires and manual is just for all others?

[Steve Carlton]

This symbol means max load. Is there another page in your owner's manual?

[ramonesfreak]

Just double checked. Nope. The entire tire pressure chart/table in the manual has that symbol. I have an oil change next week so I’ll ask when I’m at dealer.

Seems the longer I live, the more confusing the world around me gets :-(

Thanks!

[Noah930]

Wow. 48 PSI seems awfully high. Especially for such a small car. I thought the 44 PSI specified for the rear tires of my 930 was high. Not sure why there would be different recommendations from door sticker to owner's manual, though.

[ramonesfreak]

Well, they are low profile run flats so I can understand high, but 48 seems way high….

[asphaltgambler]

The door tire pressure decal is the rule, but know the specs are for full occupancy. So most don't carry all the people and baggage all the time. I'd subtract 2 psi from the decal specs and start from there for best ride quality.

[Alan A]

48 is quite the pressure. Even the daily is only at 40 and that’s 6000+lbs plus my fat ass.

[masraum]

I'm not an expert, but no way in hell I'd run the pressures listed in the book (when cold)!

Maybe the book pressures are "hot" pressures vs cold on the door sticker?

[ramonesfreak]

Nope. The manual clearly says all pressures listed are to be measured when cold

[Por_sha911]

The owners manual is usually for the base tire size that comes with the base model. The door sticker is for the specific tire size that came with that particular car (what is on the window sticker). If the car has an upgraded tire (like 18's versus base model 16's) there are different recommended pressure. Run-flats may also have different requirements.

[Scott Douglas]

What is the max pressure listed on the tire itself?

A 40 series tire is going to need that pressure to withstand hitting an edge on a pot hole or other road hazard.
I run my 45 series tires at 40 psi on my Honda. Yes, it's a harsher ride but the tire 'works' at that pressure rather than being worked by the weight of the car.

[masraum]

Originally Posted by ramonesfreak

Nope. The manual clearly says all pressures listed are to be measured when cold

Those tire pressures in the manual are crazy. I've never seen pressures that high on a regular passenger vehicle. I wonder if those are in the manual because they provide the best efficiency or something.

Originally Posted by Por_sha911

The owners manual is usually for the base tire size that comes with the base model. The door sticker is for the specific tire size that came with that particular car (what is on the window sticker). If the car has an upgraded tire (like 18's versus base model 16's) there are different recommended pressure. Run-flats may also have different requirements.

He posted an image of the manual, and the manual specifies tire sizes with the pressures.

[ramonesfreak]

Originally Posted by Por_sha911

The owners manual is usually for the base tire size that comes with the base model. The door sticker is for the specific tire size that came with that particular car (what is on the window sticker). If the car has an upgraded tire (like 18's versus base model 16's) there are different recommended pressure. Run-flats may also have different requirements.

The owners manual has a page for each model….the base, the S…the JCW…. The page I reference above is for my model, JCW, , with my wheel…same as door sticker…..actually I have both sets of wheels circled in the manual, OEM 18s with summers and OEM 17s with winters….the door sticker says nothing about 17s so that presents another mystery

[ramonesfreak]

Originally Posted by Scott Douglas

What is the max pressure listed on the tire itself?

A 40 series tire is going to need that pressure to withstand hitting an edge on a pot hole or other road hazard.
I run my 45 series tires at 40 psi on my Honda. Yes, it's a harsher ride but the tire 'works' at that pressure rather than being worked by the weight of the car.

I’ll check tomorrow. They are run flats so I expect a high psi to protect the sidewalls from damage

[Scott Douglas]

I've found my tires wear better at the higher pressure. They're 19" and I found some Goodyears that were on sale that are the same as what they put on Tesla's.