I never realised how much difference tyre pressure can make. Since fitting the adjustable sway bar and playing around with the settings I started 'fine tuning the handling' by experimenting with different tyre pressures. Maybe without the sway bar the back end was so loose tyre pressures had little effect. It always surprised me that car manufacturers and tyre manufacturers specify such LOW pressures. Guy who my alignment goes for very high pressures (38 psi = 262 Kpa), which makes the ride hard. Funny thing he inflates front and back to the same pressure. I used to run 235 kpa (32psi) front and 215 kpa (29 psi) at the rear. Most of the weight is in the front. Now it looks like (sway bar on it's firmest setting) 245 kpa (33 psi) front and 225 (30.5 psi) rear is not enough...cornering almost as good as higher pressures, but at speed on highway the car is not as stable as with higher pressures. I am starting to think the rear tyres should be inflated to the same pressure as front tyres (or close). BTW tyres are standard 205/65 15 inch.
Does anyone know whether low profile tyres need more air?? I always said the flexing of side walls with standard tyres is not as much as people claim, now I am starting to think it is a significant factor (I have been pushing harder through corners a lot in trying out and enjoying the swaybar). The pressures the alignment guy used 38 psi (262kpa), although giving a rough ride made the car handle real well and the straight ahead travel was good. maybe at this high pressure the side wall flex is minimised. At the pressures i used to run 235 (32psi) front and 215 (29 psi) rear my tyres showed perfect wear, but he claims 38 psi is needed to give even wear.

On a standard 60 profile tyre, 38 would most definately be too high, and possible cause uneven tyre wear down the centre of the tyre due to bulging. Low profile like 45 are less prone to this bulging so technically you will get even tyre wear at this pressure. I run 40 in the front and 37 in the back and that seems to be very good in terms of handling. Little bit harsher ride but still comfortable

i have 17' 45 235 and i run anywhere upto 42psi froont 40psi rear... yes its hard but corners are a dream. usually run 40 front 38 rear..

My AWD has original wheels(7" x 16) with 215/60 tyres(Bridgestone Grid III). Wear on the tyre shoulders was terrible running at stock pressures and the handling wasn't great. Progressively increased the pressure and am happiest running 39.5psi front and 36psi rear. Handles better, less tyre squeal and shoulders aren't burning up like they used to.

On the narrow 6" wheels most Magnas use I would expect that up around 38psi front and 35psi rear would be a good compromise between handling, wear and ride comfort.

Cheers, Alan

you guys would be amazed at how much your tyre pressures jump around between hot and cold

on the track with street tyres on my evo my tyre pressure was 38psi cold...went out for a session..

did a cool down lap, came in, check tyre pressure it was 47psi... i dare say it had dropped a bit from the slow cool down lap..... so if your driving hard enough you COULD see an increase of 10psi like i saw.. thats on the track.. street would prob see an easy 5psi increase at high speed with some decent corners...

its something to consider when checking your tyre pressure (where are about to drive? high speed, track, city etc)...

I run 40psi f&r, but I'm on 18s... On 15/16's I wouldn't run anywhere near that, 36 at most.

I run 40psi f&r, but I'm on 18s... On 15/16's I wouldn't run anywhere near that, 36 at most.

why?

why dont u like higher pressure in 15/16s?

40 PSI in 215/60r16's

Running on King L front/SL rears with front and rear whiteline bars and a strut brace.

Feels too spongy on 36 or so.

Tyres appear to be wearing evenly.

40 PSI in 215/60r16's

Running on King L front/SL rears with front and rear whiteline bars and a strut brace.

Feels too spongy on 36 or so.

Tyres appear to be wearing evenly.

stock 15's, running 38 front, 36 rear.

the ride feels so much nicer - and pretty even tyre wear.

why?

why dont u like higher pressure in 15/16s?

Wouldn't it be dangerous? Air expands, when you have twice as much air to expand PSI could raise by 15 or so to dangerous levels and pop go your tyres!

Wouldn't it be dangerous? Air expands, when you have twice as much air to expand PSI could raise by 15 or so to dangerous levels and pop go your tyres!

it wont raise by 15psi on the street ever.....will jump by a few pounds with some hard driving for sure but u will never get to a dangerous level driving on the street in a magna with 15s on it.... 40psi on stock wheels is totally fine.. probably hit 45psi at most if you were going crazy for along time... think about ppl doing smoke shows on stockies.. imagine the heat then... the tyres dont blow out from this.. they can handle a heap of pressure..



manufacturers like lower pressure for comfort in cars such as magnas..

I run my 235 x 18 Falkens at their maximum recommended pressure which is 50 PSI. Tyre are too hard for comfort, but very stiff with little sidewall flex I can feel may drop down a few PSI. Remember max tyre pressures will be conservative, some sites say that there is a very conservative safety factor built in and that pressures should be able to double without tyres exploding, more chance of exploding tyres from damaging the side walls from pinching, or damaged rims from low pressure.

I run my 235 x 18 Falkens at their maximum recommended pressure which is 50 PSI. Tyre are too hard for comfort, but very stiff with little sidewall flex I can feel may drop down a few PSI. Remember max tyre pressures will be conservative, some sites say that there is a very conservative safety factor built in and that pressures should be able to double without tyres exploding, more chance of exploding tyres from damaging the side walls from pinching, or damaged rims from low pressure.

mate 50psi is WAY over inflated.. there is no need what so ever for that.. id say at that pressure you'd be getting un even tyre wear and the tyre would not be perfoming at it should on the street

i run 36psi in my magna with my 19", its rides nice about that pursure

i run 36psi front and back and get even wear across the tyre. i am considering adding 2 psi to the front, although im mostly doing family dutys like taking the kids to school so high speed cornering isnt an issue lol

I run my 235 x 18 Falkens at their maximum recommended pressure which is 50 PSI.

Tyres should generally never be inflated to maximum pressure stated on the sidewall. Most good quality tyres are 44psi or 50 psi rated maximum. As the pressures increase with heat and moisture in the tyre a cold pressure of 40psi could increase to 45 psi or more with a loaded car or running at highway speeds. Hard driving could see it rise to about 50 psi. (Nitrogen filled tyres, tyres that have been dried in the sun before fitting and being inflated, and those inflated from a dry source of compressed air have a smaller pressure rise when hot.)That is too high for good handling as the tyre contact area on the road gets smaller at very high pressure and the rubber bounces and vibrates over the high ridges of the road surface rather than deforming down into the uneven surface of the road.

Stiff wall race tyres typically are inflated at about 18-20 psi cold and this rises to 32-33psi hot.

Cheers, Alan

i run 36psi in my magna with my 19", its rides nice about that pursure

That seems way too low? A pot hole comes along and your 19s = ****ed.

i used to run 38 to 40 on my 18s, handled much better compared to 36psi. recently got new tyres and are inflated with nitrogen, It handles MUCH better and only have to be reinflated or checked every 6 months..

to much air and your car will wear themiddle of the
tyre not enough and it will wear the outsides
of the tyre i find 36 is good with larger cars and the whole
tyre wears evenly

That seems way too low? A pot hole comes along and your 19s = ****ed.

thats what the tyre shop told me to put in them

thats what the tyre shop told me to put in them
Should be somewhere between 40-45psi iirc for 19s, it'll ride a bit harder, but less risk of rim damage if you hit a pothole too hard. Most people I know on 19s run 40-42psi.

it wont raise by 15psi on the street ever.....will jump by a few pounds with some hard driving for sure but u will never get to a dangerous level driving on the street in a magna with 15s on it.... 40psi on stock wheels is totally fine.. probably hit 45psi at most if you were going crazy for along time... think about ppl doing smoke shows on stockies.. imagine the heat then... the tyres dont blow out from this.. they can handle a heap of pressure..



manufacturers like lower pressure for comfort in cars such as magnas..

what did you run in your 20's gremlin?

when i went to chris(the fella who does all of cummings suspension(sh*t hot)) i had stockies on and he told me to run them on 38psi for best performance

what did you run in your 20's gremlin?

when i went to chris(the fella who does all of cummings suspension(sh*t hot)) i had stockies on and he told me to run them on 38psi for best performance

38psi in stockies is good

i used to run 42psi in my 20s.. never had an issue with cracking etc

I have always been lead to believe that the maximum pressure rating on a set of tyres is not independant of the type of tyre and that each tyre would have the best performance / wear etc depending the design of the tyre.
If Falken decide that their tyres perform best at 50 PSI I would assume they should know. I will email Falken to find what their recommendations are. I thought that 50 is too high a pressure, but the 912's do have rounded sidewalls to make the tyre run quiet, much quieter than the potenzas I normally use on my other cars. I would hardly think that If they recommend a max of 50 KSI cold that they will balloon or wear unevenly in the center as the tyres must be designed for these pressures, but I dropped the pressures to 45 because they were too hard. BTW these tyres were inflated to this pressure when bought new a couple of weeks ago by Bob Jayne.

I have always been lead to believe that the maximum pressure rating on a set of tyres is not independant of the type of tyre and that each tyre would have the best performance / wear etc depending the design of the tyre.
If Falken decide that their tyres perform best at 50 PSI I would assume they should know. I will email Falken to find what their recommendations are. I thought that 50 is too high a pressure, but the 912's do have rounded sidewalls to make the tyre run quiet, much quieter than the potenzas I normally use on my other cars. I would hardly think that If they recommend a max of 50 KSI cold that they will balloon or wear unevenly in the center as the tyres must be designed for these pressures, but I dropped the pressures to 45 because they were too hard. BTW these tyres were inflated to this pressure when bought new a couple of weeks ago by Bob Jayne.

maximum rpm of your car is 6800rpm or there abouts.. doesnt mean mitsu want you to take the car to 6800rpm before you change gear

they have to tell you the maximum pressure the tyre can handle. if the max is 50psi and your putting that into the tyre when cold then when you start driving you will exceed 50psi...

Falken arent trying to tell you their tyre performs best at 50psi. they are saying please do not exceed 50psi... i would never put more than 40psi in that tyre, cold...

If Bob Jane inflated your tyres to 50psi then there insane.. dont no what there deal is.... maybe some inexperienced apprentice has read the side wall of the tyre, found the max pressure and decided that was the amount of pressure he should put in....

i like to inflate the tyres to 75% of their max cold inflation pressure
this works out to: 70@32psi, 65@34psi, 60@36psi, 50@38psi, 40@40psi

i like to inflate the tyres to 75% of their max cold inflation pressure
this works out to: 70@32psi, 65@34psi, 60@36psi, 50@38psi, 40@40psi

Why?

What are the numbers about?