more on 348 handling

That is interesting.

What have you found are the "correct" pressures, and does it differ between tyre brands etc.?

I ask because there are large differences between the "recommended" pressures in my owners manual depending on the brand of tyre fitted, what it says on the compliance plate, and what other people say for my 355.

How on earth do you work out what to do with these cars, or is it just trial and error?!

Especially considering tyre technology has moved on so much since these cars were built it seems dopey to rely on the owner's manual.

 

+1 pls advise what tires/pressures you were playing with?

 

Are you sure that's correct? 2.0 bar for the rear tires seems awfully low.

 

Ok if you are running stock tires.

I am running 235 in the front and 295 in the rear and had the car balanced and aligned and use 38 & 40 psi.

Kai

 

2 bar rear and 2.2 bar front? - Are you sure that's correct? - The rear tyre pressures are lower than the front tyre pressures?

According to My owners manual, the original pressures for both Bridgestone RE71's and Pirelli P 700 Z should be:

Front: 2.4 bar
Rear: 2.6 bar

My RWD BMW's have also always had a higher pressure for the rear, drive tyres than the front tyres (Currently My E36 328i Sport runs 2.2 bar at the front and 2.4 bar at the rear).

My Mother has only ever owned front wheel drive cars and the quoted pressures for those cars have always been higher for the front, drive tyres than the rear tyres.

 

Seems odd to me too. I always have higher rear pressures in ALL my RWD cars, currently Ferrari and Lotus.

Both on road and track.

 

I use 32-35 for just driving around town and to increase mileage. When we're doing canyon runs, it goes down to 29-32.

 

On my 348, my ideal pressures was 29-29.5 psi f/31-31.5 psi r. Above 30 psi in front and 32 psi, the car would start to get bouncy - I guess my roads weren't particularly smooth. I had a pretty strong amount of camber - maybe this was exacerbating the ride issues.

I never tried to go lower in the rear compared to the front because of the rear bias in the weight.

 

Yes sir, as you know all the rage in the Aussie section is FChatters talking about tyre pressures all the time.

Softer tyre = more grip is my understanding.

I recall some 308 guys dropping their tyre pressures to as low as 19psi from memory for their track days.

Soft compound gives more grip, as does lowering your tyre pressures.

Same, but different.

 

As the tires get softer and develop more traction, they also develop more heat.
Heat cause tire pressures to rise.

The trick to all of the above is to get the tire rubber to the correct temperature range (about 200dF) and adjusting tire pressures so that the tires run at the right temperatures. It really does not mater what the tire pressures are if the tire tread temperature is in the right range.
It does not surprise me to find high grip tires being run at relatively lower tire pressures.

 

Well you're never too old to learn something new!

Having done a bit of reading up, I bow to your superior knowledge Sir!

It is correct that for certain models, Ferrari recommend lower rear tyre pressures than the front tyres for Pirelli and Bridgestone tyres (For Michelin tyre though they recommend having higher rear tyre pressures than the front tyres).

Coming from BMW's, I've always had the rear tyres at a higher pressure than the front tyres regardless of tyre brand!

My apologies for doubting you Sir!

 

Now that's an enthusiasts way of putting it if ever there was one!

 

Mine also match exactly your spec for Bridgestone. See photo below from the door frame sticker.
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Cheers boys.

 

A good few years ago, I had my 348 around the Top Gear track against a new 360 and a 355F1 with a Challenge wing - all for a Channel 5 TV show. A great tip given to me by Graham Reeder (a very good race Champion) was to take 8 lbs pressure out of the tires. It really worked as I was within 0.1 sec of the 360 and 2.5 secs faster than the 355.

Basically, by the time the tires had warmed up on the track, they were at a perfect temperature for best grip. Otherwise they would have had far too much pressure and a great fall off in grip.

For road use the stock pressures are by far the best.