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Discussion Starter #1
Has there been any decisive conclusions as to what tire pressures are best for the classic 900?
I am running @ 34 lbs right now, but seem to remember 37?:confused:
Thank you!
 

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scubasaab said:
Has there been any decisive conclusions as to what tire pressures are best for the classic 900?
I am running @ 34 lbs right now, but seem to remember 37?:confused:
Thank you!
The owner's manual PDF I'm sure we've all downloaded says 2.1bar front, 2.2bar rear below 160kph/100mph and without 4+ passengers. That converts to 30 F/32 R psi.

For fully laden, 100mph+ it suggests 2.5/2.6 bar, 36/37psi - but for normal use 37 seems ridiculously high to me. I don't think I've ever come across anything recommending normal pressures that high this side of a largish van. The ride'll be harsh, the handling skittish, and the tyres'll wear the centre out rather than evenly.
 

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TooMany2cvs said:
That converts to 30 F/32 R psi
Yeah, that's what it says on the back of the sunvisor here. I find, though, that the tires wear as if they are underinflated if you use those pressures. Also, it makes the body roll like a caddilac in high speed corners. I've been doing anywhere from 34-36 (measured while cold), and seem to get even treadwear. The handling is crisper with better feedback, although heavy bumps can be somewhat harsh. For what it's worth, two longtime saab indies that I know both run their c900s in this range as well.

I don't know if it makes a difference that I have larger (205/50/16) tires.
 

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I run 32 front and 34 rear, and the tires seem to wear evenly, and the ride is acceptable, to me anyway.

Bumping up a couple of pounds if going for a fully laden banzai run would make some sense, I suppose!
 

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Gabby said:
I run 32 front and 34 rear, and the tires seem to wear evenly, and the ride is acceptable, to me anyway.

Bumping up a couple of pounds if going for a fully laden banzai run would make some sense, I suppose!
I agree with you here, for years I ran Front 30PSI Back 32PSI, and found it a bit soft, especially on fast cornering. Now I go with 32PSI and 34PSI and notice a great improvement.

BTW on 195/60 15 the Pirelli P7's are excellent, definately better than the P6000. Black Circles do them for about £65 a corner all in. :D
 

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Discussion Starter #6
Thanks for all the replies folks!!
I have one last question...
The pressure being lower in the front is counterintuitive to me.
As the front of our cars weigh a lot more than the rear, would not having the rear lower than the front (with the correct pressures) give us the flattest (largest contact patch) placement of rubber on the road?
Thanks!!
 

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scubasaab said:
Thanks for all the replies folks!!
I have one last question...
The pressure being lower in the front is counterintuitive to me.
As the front of our cars weigh a lot more than the rear, would not having the rear lower than the front (with the correct pressures) give us the flattest (largest contact patch) placement of rubber on the road?
The actual amount of contact patch isn't hugely relevant - what is is the amount of pressure exerted on the ground by that contact patch. Basic physics says that that ground pressure is the same as the tyre pressure.

So the front gets a larger contact patch but a slightly lower ground pressure. Since the front is exerting forces in far more directions than just downwards - unlike the rear - that lower ground pressure helps the tyre to grip that bit more.

The rear pressure is set more for neutral handling.

Or something. I think.
 

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Run 34 in the Front and 32 in the back.

I want turn in, and the double wishbone suspension will do the rest...
 

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Saab says to put less in the front because it promotes understeer, which is seen by car manufacturers as a "safe" recommendation for the average joe driver.
 
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