Tyre pressures

wildfaye · Post by **wildfaye** » Tue Mar 29, 2005 12:43 am

HI guys, I hope this is the rite forum to put this thread...

okie...the stock tyre pressures for the 205/50r16 is 220kpa front 190 rear

if i upsize to 215/45r17, do i have to increase e pressures?

my fave tyre shop recommends that upsizing oso requires a 10% increase, namly 240-250 front and 210-220 rear...

any logic in that? or shld i jus go with stock...this has baffled me for ages...

thanks everyone...

HiRAEdd · Post by **HiRAEdd** » Tue Mar 29, 2005 6:52 am

The general rule with all tyres is add 10% to whatever the manufacturer recommends. This is because the values the manufacturer recommends are based on maximum comfort, not maximum performance (and safety).
Going up to 17 inch wheels should involve another slight increase on top of that. I haven't done the maths yet but when I went to 17s, the tyre shop said I should be running them at about 36psi.

afterburner · Post by **afterburner** » Tue Mar 29, 2005 7:48 am

Yeah I run between 35 and 40 psi in my 17" tyres. In general with low profile tyres you want to run pressures towards the upper end of the range for the reasons mentioned above, and also so that it reduces the risk of denting or damaging your wheels if you hit a hard bump, curb, railway line, etc at reasonable speed.

wildfaye · Post by **wildfaye** » Thu Mar 31, 2005 2:00 am

I got mine fitted today...e guy recommended 260 kpa front 240 rear...

I'll prob have to drive it around before actually deciding on wats best...

err...any conversion charts to recommend? i cant figure out psi vs kpa...

HiRAEdd · Post by **HiRAEdd** » Thu Mar 31, 2005 6:55 am

wildfaye wrote: err...any conversion charts to recommend? i cant figure out psi vs kpa...

http://www.onlineconversion.com/pressure.htm

Post by **smorison** » Thu Mar 31, 2005 10:57 pm

i run HOT temps of
36psi normal driving
40psi track and performance

as the tyres get hot they increase in pressure... depending on road conditions and ambient temp the hot pressure can vary...

(e.g. a lot of right hand corners will heat up the left hand tyres more - front more-so than the back)

wildfaye · Post by **wildfaye** » Fri Apr 01, 2005 1:26 am

Thanks gavin!! great site for conversions!

smorison: is your 36psi all round for normal? 40psi all round for track?

i thot the handbook recommends 220kpa front and 190 rear?
wats the consequences of higher pressures? better handling? lower consumption?

Front: 260 kilopascal = 37.7098119 pound-force/square inch (PSI)
Rear: 240 kilopascal = 34.8090571 pound-force/square inch (PSI)

They put in nitrogen for me...its sposed to be more inert then normal compressed air...hence let temp changes...

HiRAEdd · Post by **HiRAEdd** » Fri Apr 01, 2005 6:58 am

Unless you always top up with Nitrogen, it's such a crock of $hit.