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Discussion Starter #1
I have just fitted 18" rims and 225/40/18 to my 156 JTD what should the tyre pressures be?

Thanks
 

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I use 36 psi front, 34 psi rear
 

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I have just fitted 18" rims and 225/40/18 to my 156 JTD what should the tyre pressures be?

Thanks
Tyre pressures will be the same as with standard wheels, or whatever the handbook says.

The cars weight dictates the tyre pressures, not the tyre size. Something to do with the laws of physics apparently.
 

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Tyre pressures will be the same as with standard wheels, or whatever the handbook says.

The cars weight dictates the tyre pressures, not the tyre size. Something to do with the laws of physics apparently.
i thought lower profile tyres needed more psi to stop them from damaging the wheel and over flexing the side wall?

but you know what thought did:lol:
 

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You can play with the pressures a bit, but the general rule is to start with the original pressures.

I can't remember where I got this info from but it might have been carbibles.com :)
 

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You can play with the pressures a bit, but the general rule is to start with the original pressures.

I can't remember where I got this info from but it might have been carbibles.com :)
so the tyre pressure for 15" tyres are the same for 18" tyres, that doesnt sound right:confused:

im getting confused again:rant::lol:
 

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The pressure required to support the weight of the car is the same no matter what sized tyres are fitted.

I didn't believe it either at first..
 

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Hi Mate .... I asked a similar question a couple of days back for my GT - the response was:

Minimum pressures are:
Front 36PSI
Rear 35PSI

For full load they need 41PSI front and 39PSI rear.

They really do know a lot these forum guys :)
 

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just purchased a set of 18" 225 40 18 of ebay have you had any trouble with them rubbing bit worried i should of gone with 17s but biggers better right
 

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Discussion Starter #13
Thanks for all the replies I think I have the answer 2.4bar it is!

No problems with rubbing or anything else overall rather pleased with the result.
 

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Bigger is not necessarily bette,r malc156. But they wont rub if its not been lowered, they might if its been lowered more than 30mm though.
 

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The pressure required to support the weight of the car is the same no matter what sized tyres are fitted.

I didn't believe it either at first..
sorry i beg to differ if you take itt to extremes and see pressurse for tractors and thin push bike tyre ,i was told by a contenental tyre technician from the factory that lower the profile the increase in pressure, i suggest a call to tyre manufacture and remember some tyre manufactures stippulate diff pressures for their tyres,its all to do with construction use etc :thumbs:
 
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