Tyre Pressures
- Thread starter Geezah
- Start date
There isn't really a "definitive" set of pressures since tyres have a fairly wide operating range. I went from OEM Bridgestone RFTs to Vredestein Sessantas and matched the loads (using a chart) to find the right pressures for the new tyres:
OEM:
225/40R18 88W @ 33psi = 519kg load
255/35R18 90W @ 36psi = 600kg load
Vreds:
225/40R18 92Y XL = 519kg load @ 33psi
255/35R18 94Y XL = 603kg load @ 37psi
So OEM pressures are a sensible starting point for the Vreds because they have a higher load rating than the Bridgestones, but require higher pressures than a non-XL tyre at any load below their maximum rating (which is achieved at 40psi+, I think).
Since then I've experimented a bit and am currently running 30psi front and 32psi rear. The ride is great but turn-in feels a bit woolly. Not quite sure what to do about this yet since the front tyres feel a bit "floaty" at OEM pressures. Might try 32psi all round next.
OEM:
225/40R18 88W @ 33psi = 519kg load
255/35R18 90W @ 36psi = 600kg load
Vreds:
225/40R18 92Y XL = 519kg load @ 33psi
255/35R18 94Y XL = 603kg load @ 37psi
So OEM pressures are a sensible starting point for the Vreds because they have a higher load rating than the Bridgestones, but require higher pressures than a non-XL tyre at any load below their maximum rating (which is achieved at 40psi+, I think).
Since then I've experimented a bit and am currently running 30psi front and 32psi rear. The ride is great but turn-in feels a bit woolly. Not quite sure what to do about this yet since the front tyres feel a bit "floaty" at OEM pressures. Might try 32psi all round next.
I've checked out the figure on the door pillar and its giving:
2.0 bar for the front (29 psi) and 2.2 bar for the rear (32 psi) Yet most of you seem to be running much higher. Does this not cause you any excessive tyre wear in the tyre centres and perhaps make tramlining and ride worse?
2.0 bar for the front (29 psi) and 2.2 bar for the rear (32 psi) Yet most of you seem to be running much higher. Does this not cause you any excessive tyre wear in the tyre centres and perhaps make tramlining and ride worse?
Hi all,
Ok and i know this isn't the common thing to do but i replaced my rear RFT with new RFT mainly due to the front being new a year ago before i brought the car.
Anyway while speaking to guy in "the tire shop" in E4 and discussing Vreds he said he would run the tires about 4lb more than RFT so as to give the inner wall of the more flexible Vreds RFT additional stability.
They also checked and adjusted the whole geometry of the suspension and i must say i have no complaints and the car just seems more planted and with a lot more feed back through the steering.
Ok and i know this isn't the common thing to do but i replaced my rear RFT with new RFT mainly due to the front being new a year ago before i brought the car.
Anyway while speaking to guy in "the tire shop" in E4 and discussing Vreds he said he would run the tires about 4lb more than RFT so as to give the inner wall of the more flexible Vreds RFT additional stability.
They also checked and adjusted the whole geometry of the suspension and i must say i have no complaints and the car just seems more planted and with a lot more feed back through the steering.
Hmm - I've been running my Zed at 28 fronts and 32 rear (2006 2.0i sport). I assume RFT need more pressure due to the stiffer tyre wall?
I may experiment but I found 36 affected turn in on the front Goodyear Eagle F1s - lacked bite and feel. Have always run the backs at 32. . . ?!
I may experiment but I found 36 affected turn in on the front Goodyear Eagle F1s - lacked bite and feel. Have always run the backs at 32. . . ?!
I have a similar question - today I've just put non RFTs Falken HS 439 in 225/45/17 and 255/40/17 on my Z.
Any recommendations on which pressure should they be running? I think the fitter said he out 34 psi all around, but wanted to double check with you folks.
Any recommendations on which pressure should they be running? I think the fitter said he out 34 psi all around, but wanted to double check with you folks.
I have found these all seem okay on a 2.0 with F1 asymmetrics.
32 32
34 34
32 34
35 37
I have been tending towards higher pressures because petrol consumption seems slightly better with harder tyres.
Let us know what you settle on.
32 32
34 34
32 34
35 37
I have been tending towards higher pressures because petrol consumption seems slightly better with harder tyres.
Let us know what you settle on.
I spoke with these guys http://www.tyresafe.org/ The lady I spoke to told me that the tyre pressures given by BMW albeit for the supplied RFTs should be the same if the car is fitted with non RFTs. The place where I took my car for 4 wheel alignement, who comes highly recommended by all the petrol heads around here told me the same thing.
So....my door pillar says 2.0 bar fronts and 2.2 bar rears, but as with everything I guess it's a trade off between better grip (softer tyres?) and better fuel economy (harder tyres?)
I make that 29 psi fronts and 32 psi rears, I'll see how it goes (Vred Ultrac Vorti, 225/18/40 and 255/18/35)
So....my door pillar says 2.0 bar fronts and 2.2 bar rears, but as with everything I guess it's a trade off between better grip (softer tyres?) and better fuel economy (harder tyres?)
I make that 29 psi fronts and 32 psi rears, I'll see how it goes (Vred Ultrac Vorti, 225/18/40 and 255/18/35)
1066 Country
Seems to vary wildly depending on tyre types - here's my experience of summers & winters with even tyre wear
SUMMERS - Michelin PS3's nonRTF's
Front 33psi (225.40.18)
Rear 36psi (255.35.18) - anything approaching 35psi & below & rear end starts to get slightly soggy
WINTERS - Vred Wintrac extreme non RFT's
Front 32.5psi (225.45.18)
Rear 33psi (225.45.18) - anything over 33psi & rear end gets skittish on damp surfaces
have fun
SUMMERS - Michelin PS3's nonRTF's
Front 33psi (225.40.18)
Rear 36psi (255.35.18) - anything approaching 35psi & below & rear end starts to get slightly soggy
WINTERS - Vred Wintrac extreme non RFT's
Front 32.5psi (225.45.18)
Rear 33psi (225.45.18) - anything over 33psi & rear end gets skittish on damp surfaces
have fun
Jembo said:
36 psi in the rears tomorrow for me then :wink:
Traction control light on all the time...... :wink:Jembo said:Talksthetorque said:Jembo said:
36 psi in the rears tomorrow for me then :wink:
Only if you like your traction control light flashing more than your Xmas tree & don't mind being overtaken by Miss Daisy....
Need to clean the side windows first though so I can see where I'm going