Hi Guys, I tried doing a search but no luck. I just bought a 99 360M coupe and was looking at the tire pressures stated in the manual for the Michelin PS tires. It says to run 29 psi (cold) front and rear. Then I came across the owner's manual for the 2000 model and newer. I noticed the tire pressures listed for the PS tires are 26 psi front and 28 psi rear. I was wondering if someone can give me more info on this. Was there a change in suspension set up or the car in general between a 99 360M vs. a '00 or newer 360? I'm just curious since I want to know which tire pressures I should be following. I would appreciate any info you guys can give me. Thanks, Alex
Those tyre pressures are way way too low. All manufacturers recommend pressures which are too low for the car to give a more 'cushy' ride. But this will adversely affect handling, and result in excessive and uneven tyre wear - especially for a car like a Ferrari 360. Considering the type of car, engine location (mid), drive location (RWD), and tyres, I'd recommend at least 36psi at the front, and 38psi at the rear. This pressure differential between front and rear will provide better balance than even pressures all round. Normally this doesn't make that much difference with a normal car, but again, in this case it's much more important. If I owned that car, I'd put 38psi in the front and 40psi in the rear.
And you'd have a tail happy monster that wears the middles of its tyres out.... Most low profile cars (F40/348 to date) use a lower pressure in the rear. The low profile tyres have a low volume of air. As the rears work very hard, the temperature and consequently pressure change is high.... thus, once hot the rears will raise their pressure much more than the front. Don't confuse BAR with PSI or Kpa Cold pressures are when the tyre is cold, as in not driven on at all, or VERY briefly. If the tyre is quite hot, or warm, your pressures will be up by around 3-6 psi. On track, they'll come up maybe 10-12 from their cold pressure. I'd start at 34psi cold rear, 36 psi cold front and see how it feels to you.
Yes, but are we talking about track driving or street driving? 38 psi is not high enough (with low profile tyres) to wear out the middle of the tread excessively. I suggested higher pressures in the rear (for the street) because the weight in the 360 is concentrated in the rear, and the weight will transfer to the rear under acceleration.
on '04 360 suggested pressures are 2.2bar in the front and 2.0bar in the rear (you do the conversions in PSI). The 'sporty drive' explanation why front should have higher 'cold' pressures makes sense...
Thanks for all the explanations. I have a pretty good understanding on tire pressures and using it to fine tune the balance of the car. I just think some of the pressures stated are very high. I've tried different pressures for the street and the ones stated on the owner's manual is a pretty good basis to start with. I think +/- 2 psi from recommended is fine for the street. They recommend specific pressures for particular tires. So my question really was for the Michelin PS pressures, which on the '99 Owner's manual stated 29 psi all around. While the '00 and newer owner's manual stated 26 psi front and 28 psi rear for Michelin PS tires. I was just wondering if any of you knew why they changed the recommended pressures in the owner's manual. I'm assuming the lower pressures in front for the newer cars were done to create a bit of understeer. As a rule of thumb, 1 psi is equivalent to 20lbs. of spring rate. So by going all the way to 38 psi (cold) from 29 psi (cold) would add 180 lbs. of spring rates, which I think is too high of a jump for a stock car, especially if you meant that 38 psi is cold and not hot pressures. FWIW, I check my pressures and condition of tires every week, and the tread wear is even (using factory recommended pressures). I also know the pressures used by the previous owner of my car is with in factory spec. I am sure some will disagree with some of my thoughts, but I would like to hear more people chime in on this if possible. I've done a search and have not seen anything covering this topic in depth. Thanks to all that responded. Alex
To really answer this question you'd need a tire temperature gauge to check the temps across the tread. The other big variable is how much and hard you're cornering compared with how much time you're on the freeway or going straight. Hard cornering will wear the edges of a tire with too little pressure, while going straight will wear the center of a tire with too much pressure. So the correct pressure for you will depend on how you're using the car. But I'd be loathe to run higher pressures in the front than the rear, as there's much more weight on the rear.
But the cold pressures are what is usually most convenient to check at home before you drive it. Once you've driven it, even just moderately on the road, the pressure will still rise more on the rear than front. For example, if you drive 15 minutes along a "nice" strecth of road before checking your tyres at a fuel stop, you'll find the pressures will alrady have equalised F-R most likely. Finally.... NEVER trust someone else tyre pressure gauge. Get your own and stick to it. Variations are common, and it's comparitive readings that you're after to establish what is best for you, depending on your specifics. To answer the original question.... NO idea!! Handbooks have MANY typos and mistakes in them, but I can only assume that the tyre manufacturer has listened to feedback now that the cars are older and have recorded useful info... and have modified their advise.
i have a 2004 360 spider. the label on the passenger door jam says 29 psi front AND rear, so i don't know what is right about front versus rear. as mentioned before, the right way to determine it is with a tire temp. gauge (pyrometer). in bob bondurant's book, High Performance Driving, he says, "Take the temp. of three areas: the outside, middle, and inside on top of the tire. .....If they look like this: outside 180, middle 290, inside 200, you have too much air. Drop the pressure by 5 pounds and try it again until you get fairly even temperatures and you will find your car handling better." earlier he mentions the hazards of too low a pressure and the sidewall deflecting and being sloppy in the corner, or worse yet, coming off the rim. this is all applicable to hard driving on the track. hope this helps, edwin_360
My '02 360 Modena says 29 rear, 32 front. I believe my car came with Pirelli's and now has Michelins. I don't know if that makes a difference?
Jon, The manual recommends different tire pressures for different tire brands. You should be able to find the pressures there. Alex
Thanks, I will take a look when I get home. I thought because these are not the original tires it wouldn't be there. I appreciate the help. Jon
As to the original question there were no changes between the cars. It was a simple case of Ferrari reevaluating the handling of the car with Michelin tires and arriving at a different pressure. There was even a service bulletin generated to that effect. Ferrari does a great deal of tire testing at Fiorano with representatives of the various tire companies present. The numbers are not arrived at by a desk jocky engineer as they are with many cars.
Brian, So does this mean if my '99 owner's manual says 29 psi front and rear and the the newer manual says 26 front 28 rear, that I follow the newer pressures? Thanks, Alex
Use the later #. It has been the specified pressure since TSB#888 dated 11-2000. According to the TSB the new label (print # 178701) is available FREE of charge (good luck with that one) from FNA spare parts department. I'd of spoken up sooner but this train got off the track just after it left the station.
