I have some 20's going on my Vantage 4.3 and was wondering what pressures you guys were running.

Wheels are:

285/30/20 rear
245/35/20 front

They are within 0.8% rolling radius of OEM 19 alloys.

 

orignal pressure of 33psi front and rear 36psi is perfect..there is no reason to change pressure for 1 inch rise change in mag size.

 

Fair enough. Guy at the garage filled them 36 on both will adjust and see.

 

if we change the tire pressures because of changing temperature, do we have to reset the TPMS or do anything with the car?

 

Well first, never change/adjust the tire pressure after a long drive, tires are to hot and this affects tire pressure inside tire, always make sure tire surface is cool to the touch when adjusting pressures, unless you have a gauge to check tire temp and know how to convert temp to pressure adjustment needed..

If temp outside rises, there is no need to change tire pressures to bare with the ambient temp rise in your area. Only place you would adjust pressures due to ambient temp would be on a track where this affects the track temp..on the streets, you don't achieve high enough speeds(for long duration) and high tire temps to worry about tire pressure as a need to reduce track times/ increase top speed/ while improving mpg..

On the streets, it's a K.I.S.S priciple..stick with what is indicated on the Tire Packet label on your door...Vantage front: 33psi, rear: 36psi - DB9/DBS front: 36psi, rear: 38psi