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Tyre pressures.
http://international2cvfriends.com/forum/viewtopic.php?f=7&t=908		 Page 1 of 1
Author:  Jonathan [ October 6th, 2009, 10:07 pm ]
Post subject:  Tyre pressures.
Just been wondering about this and I'm somewhat curious.

The 375/425cc cars had pressures of 14psi front and 15.5psi rear, but only having a max speed of 40-50mph. The later 425s with 13.5bhp and 18bhp had pressures increased to 17psi front, 20psi rear, with max speed of 55-60mph. The later cars, 435/602 have them at 20psi front, 26psi rear with max speed of up to 70mph or so.

My query is this, if a late car is only trundling round London(for example) and not going quicker than about 40mph, what sort of handling/ride/tyre wear would you expect with 14psi front 15.5psi rear?

Like I said, just curious, so don't bite my head off :lol:
Author:  Joe [ October 6th, 2009, 10:15 pm ]
Post subject:  Re: Tyre pressures.
im running 125 firestones all round with 26psi each corner. i might lower it a bit to 24 in the front, things get a bit hairy in the wet!

edit, oh and ive not noticed any uneven tyre ware. but only time will tell i guess.
Author:  samfieldhouse [ October 7th, 2009, 12:21 am ]
Post subject:  Re: Tyre pressures.
I have my 135s at 26 front and currently, 30 at the back as ive been towing/camping alot
Author:  Sean [ October 7th, 2009, 9:46 pm ]
Post subject:  Re: Tyre pressures.
sopwithcamel wrote:
Just been wondering about this and I'm somewhat curious.

The 375/425cc cars had pressures of 14psi front and 15.5psi rear, but only having a max speed of 40-50mph. The later 425s with 13.5bhp and 18bhp had pressures increased to 17psi front, 20psi rear, with max speed of 55-60mph. The later cars, 435/602 have them at 20psi front, 26psi rear with max speed of up to 70mph or so.

My query is this, if a late car is only trundling round London(for example) and not going quicker than about 40mph, what sort of handling/ride/tyre wear would you expect with 14psi front 15.5psi rear?

Like I said, just curious, so don't bite my head off :lol:


<shrug>
try it and see

tyre pressure increased due to the dizzying increases in power and therefore cornering speed firmer tyres were less likley to "creep" when cornering

think im on 30 psi
Author:  TimCV [ November 8th, 2009, 1:26 am ]
Post subject:  Re: Tyre pressures.
my experience of Citroen is that they knew what they were doing - 20/26 works best for me!
Author:  Daffy Duck [ November 14th, 2009, 3:37 pm ]
Post subject:  Re: Tyre pressures.
I agree with the 20/26, although I actually use 20/22. I like a bit more oversteer (or rather less understeer). I would be louth to increase the front tyres beyond 22. (125 Michelins), as I had a bad experience with the front chattering sideways on a rough corner.

On 135 Nankangs I tend to use the same pressures (this is on a Raid car), as the firmer the tyres the greater the shock stress on the rest of the suspension. Tyres are an expendable item. Suspension arms aren't. On Raid Oz 2008, we had more problems with suspensions of cars with pressures around 30 psi.

The front tyres produce the steering, braking and handling. The rear tyres keep the bum off the road. Keep the front pressures close to specifications, the rear pressures have less influence - more in the balance of the car (oversteer/understeer).

Daffy Duck
Author:  Daffy Duck [ November 14th, 2009, 3:44 pm ]
Post subject:  Re: Tyre pressures.
One thing I forgot to add - although 14/15 was specified for a car that drove at 40-50mph; 17/20 for one at 55-60mph; and 20/26 for one at 70mph; 30/40 is NOT going to give you a car that will do 100mph. Sadly, performance improvements require something more substantive than air, generally lots of money.

Daffy Duck
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