Jimbo

I actually had a flat tire on one of my run-flats. Obviously after the tire was changed, the FTM was reset.



I also have a slow leak in another rear run flat and it keeps setting off the FTM. I need to take it to the tire dealer to replace under warranty. I top off the tire each time and reset the FTM.

I would reset the FTM each time so that is calculates correctly. It's not that big a deal.

Btw, I have Bridgestone run flats, not Dunlops.

gdavis

I think JDN said this, but I confirmed the mystery about the air pressure chart with my dealer today. He said that the listings without the symbols are for all season tires/tyres and the ones with the circles/squares etc are for the sports tires (the W or Y ratings etc.). I think that is what he said.

That is why the pressures vary for the same size tire, since they are differently rated tires. You probably already knew this, but I just caught on with it

RH530

Close

The manual says 120 Nm.

RH530

So, for those of us that have the same tire width on all 4 wheels (the non 545 crowd ) it appears that the 50:50 distribution does carry to the tires since according to the chart the circle, for example, only has one entry in the table for 4 passengers (for the front -- no rear entry). Am I to presume that this means all four tires should be at 32 psi? The manual itself makes a generic statement and suggest 30 psi in the front and 35 psi in the back.

This is indeed one very confusing topic/chart and almost requires its own instruction manual

Don Juan

The different tire pressure in the front and the rear is to keep the factory understeerr effect. As it is understeer is easier to control that oversteer. My frineds at a performance place gave me a bit pf a briefing back when I had my 3series. If i want to keep the car more to an even distribution I could use the same pressure in all tires. If I want to reduce the understeer because the rear tires are now bigger I should increase the pressure in the front. So pressure and tire size will affect the handling of the car. n this case I have 34psi in the front and 35psi in the rear . I feel the car is a bit more neutral but still feel a little bit of understeer when cornering hard. Another thing that I justnticed is that my rear tires are wearing a bit faster in the middle <_< ; like if the tire is overinflated. Very weird, I have put 12000 miles in my Pirelly Pzeros and I always keep the rears to 35 psi..

sg530

My 5 came from the dealer with higher pressure on the rear and higher pressure than the label all around. I was experiencing wheel hop on hard acceleration during a turn so I reduced the pressure on the rear a few psi and balanced the pressures with 2 psi higher on the rear. Wheel hop is reduced, ride seems same if not harder and pressure sensor didn't notice I took out 3 psi from both rears.

JDN

I brought the chart forward for reference because I get a different conclusion for those with "the same tire width on all 4 wheels." Under those conditions, I would air as follows:
Load / Low / Max
Front / 32 / 38
Rear / 38 / 45

alohalc

i'm also one of the non 545 drivers (have a 530). i've noticed the low/max diff. so is it better off to go at the middle, 35 front and 41.5 rear? most of the time i'm w/my gf and no rear passenger and almost nothing in the trunk.

JDN

I always run the low side when I only carry me or my wife. Tomorrow I will haul four people with no luggage and will likely raise two or three pounds in the morning in all tires for the occasion.

alohalc

i wanted to do this but i'm too lazy to go to the gas station, check all the pressures, pump in some air, re-check the pressures, make my hands dirty . if i run them low, i have to redo all the "hard works" more often and wear the tires a bit faster (well, i don't really care about this part). please correct me if i'm wrong.