Track day tyres - Page 2 - Bimmerfest - BMW Forums



Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > Z Series > E85 / E86 Z4 (2003-2008)

E85 / E86 Z4 (2003-2008)
E85 Z4 Roadster, E86 Z4 Coupe, E85 Z4 M Roadster, and E86 Z4 M Coupe talk with our BMW gurus here.

Reply
 
Thread Tools Display Modes
  #26  
Old 04-22-2019, 10:13 PM
Rotorblade Rotorblade is offline
Registered User
Location: Bucharest
 
Join Date: Nov 2017
Posts: 94
Mein Auto: Bmw x1
I suppose ps4s is the plural for ps4. They seem to provide good grip and I've also noticed they do very well on wet roads. The road noise is also low. Anyway I haven't use any other tires on this car so I can't make a comparison.
Reply With Quote
Sponsored Links
Advertisement
 
  #27  
Old 05-08-2019, 01:47 PM
Rotorblade Rotorblade is offline
Registered User
Location: Bucharest
 
Join Date: Nov 2017
Posts: 94
Mein Auto: Bmw x1
I went today on a small track with the 225F 255R PS4, temperature 12C, pressure 2.1 Bar Fr, 2.6 bar Re and they didn't feel as grippy as the 255F 265R ones, possibly because of the track temperature or the tire pressure!?
I also have a system, not sure exactly how it is used, but when a certain lateral acceleration is achieved there is a weight that slides on a bar and you can hear it rattle. This time it would do anything... it could be stuck also
Reply With Quote
  #28  
Old 05-10-2019, 06:23 PM
dc_wright's Avatar
dc_wright dc_wright is online now
bimmerfest Supporting Member
Location: Orlando, Florida
 
Join Date: Nov 2007
Posts: 12,545
Send a message via ICQ to dc_wright
Mein Auto: '06 Z4 3.0si, '11 128CiC
Everything else being equal, the narrower tires will have less grip as their contact patch is smaller. No surprise they felt like less grip.
__________________
2006 Z4 3.0si Sport Package (But I'll still hang with my "homies" in the E36 forum)
Reply With Quote
  #29  
Old 05-12-2019, 07:51 PM
Andyz4 Andyz4 is online now
Officially Welcomed to the 'Fest
Location: Orlando, FL
 
Join Date: Mar 2018
Posts: 216
Mein Auto: 2006 Z4 3.0si
Actually the size of the contact patch remains the same with wider tires, it just shifts it laterally.
__________________
[SIGPIC]
Reply With Quote
  #30  
Old 05-13-2019, 01:09 PM
Rotorblade Rotorblade is offline
Registered User
Location: Bucharest
 
Join Date: Nov 2017
Posts: 94
Mein Auto: Bmw x1
Quote:
Originally Posted by Andyz4 View Post
Actually the size of the contact patch remains the same with wider tires, it just shifts it laterally.
I've watched a test on different tire sizes on a 3series and it showed that for a wider size tire the pattern becomes wider but narrower (because the tire doesn't deform under the weight of the car that much I suppose) so the area doesn't increase that much. Anyway the wider tires had slightly more grip and with wider front tires there was less understeering.
Reply With Quote
  #31  
Old 05-13-2019, 07:34 PM
dc_wright's Avatar
dc_wright dc_wright is online now
bimmerfest Supporting Member
Location: Orlando, Florida
 
Join Date: Nov 2007
Posts: 12,545
Send a message via ICQ to dc_wright
Mein Auto: '06 Z4 3.0si, '11 128CiC
Quote:
Originally Posted by Rotorblade View Post
I've watched a test on different tire sizes on a 3series and it showed that for a wider size tire the pattern becomes wider but narrower (because the tire doesn't deform under the weight of the car that much I suppose) so the area doesn't increase that much. Anyway the wider tires had slightly more grip and with wider front tires there was less understeering.
The static contact patch doesn't change much with wider tires, but the dynamic contact patch changes dramatically. As you laterally load the tire and the tread starts to roll under the load the wider tire has more tread to roll through before grip drops off.
__________________
2006 Z4 3.0si Sport Package (But I'll still hang with my "homies" in the E36 forum)
Reply With Quote
  #32  
Old 05-13-2019, 08:52 PM
Andyz4 Andyz4 is online now
Officially Welcomed to the 'Fest
Location: Orlando, FL
 
Join Date: Mar 2018
Posts: 216
Mein Auto: 2006 Z4 3.0si
Yes wider tires will increase the lateral patch/lateral grip but at the expense of the longtitudinal (fore/aft) patch used for acceleration and braking. No free lunch here.
__________________
[SIGPIC]
Reply With Quote
  #33  
Old 06-05-2019, 04:09 AM
Rotorblade Rotorblade is offline
Registered User
Location: Bucharest
 
Join Date: Nov 2017
Posts: 94
Mein Auto: Bmw x1
On the front the 225 ones heat up quickly on the track, the 255's were very good. The problem is I have put the 255's on some JR11 rims which have a ET that sets them further away from the hub than the OEM ones, that's why they touched the wheel liner. Even with the 225's the clearance is not perfect. I have a set of old OEM M\\\ rims, I could try with the 255's.
Reply With Quote
  #34  
Old 06-19-2019, 08:49 AM
Rotorblade Rotorblade is offline
Registered User
Location: Bucharest
 
Join Date: Nov 2017
Posts: 94
Mein Auto: Bmw x1
I did another change, this time I fitted the car with a set of OEM M rims. Because of the proper offset these allowed me to install a pair of 245/55 R18 tires. The 8" width looks good and is within specs. On the rear I have the 255s. Now the car feels pretty neutral through the corners. If I take a corner too fast, often both the front and rear start to slide. They heat up quite quickly but anyway the engine is not prepared for sustained effort like on an M car. The oil is too thin and the engine cooling I suppose is not that effective so I think the best is to do 1 timed lap an one cool down lap. The brakes are good enough, I have upgraded them with cooling ducts.
Reply With Quote
  #35  
Old 06-19-2019, 07:33 PM
dc_wright's Avatar
dc_wright dc_wright is online now
bimmerfest Supporting Member
Location: Orlando, Florida
 
Join Date: Nov 2007
Posts: 12,545
Send a message via ICQ to dc_wright
Mein Auto: '06 Z4 3.0si, '11 128CiC
So long as the cooling system is in good condition it will be fine for sustained lapping. I have stock system and it's been fine running full 25 minute sessions in 98 degree heat.
I run either BMW 5W30 or Pennzoil Platinum Euro 10W40.
__________________
2006 Z4 3.0si Sport Package (But I'll still hang with my "homies" in the E36 forum)
Reply With Quote
  #36  
Old 06-19-2019, 07:51 PM
Andyz4 Andyz4 is online now
Officially Welcomed to the 'Fest
Location: Orlando, FL
 
Join Date: Mar 2018
Posts: 216
Mein Auto: 2006 Z4 3.0si
Quote:
Originally Posted by dc_wright View Post
So long as the cooling system is in good condition it will be fine for sustained lapping. I have stock system and it's been fine running full 25 minute sessions in 98 degree .
2x, stock cooling system is up to job. Stock brake pads? Not so much..
Reply With Quote
  #37  
Old 06-19-2019, 09:48 PM
Rotorblade Rotorblade is offline
Registered User
Location: Bucharest
 
Join Date: Nov 2017
Posts: 94
Mein Auto: Bmw x1
Thanks.
I have Ebc yellow stuff pads, ebc discs SS brake likes, RBF660 fluid, and cooling ducts down to the hub, but I didn't do more than 7minutes before a cool down lap.
Reply With Quote
  #38  
Old 06-21-2019, 07:34 PM
dc_wright's Avatar
dc_wright dc_wright is online now
bimmerfest Supporting Member
Location: Orlando, Florida
 
Join Date: Nov 2007
Posts: 12,545
Send a message via ICQ to dc_wright
Mein Auto: '06 Z4 3.0si, '11 128CiC
Quote:
Originally Posted by Rotorblade View Post
Thanks.
I have Ebc yellow stuff pads, ebc discs SS brake likes, RBF660 fluid, and cooling ducts down to the hub, but I didn't do more than 7minutes before a cool down lap.
The EBC Yellows will do OK for the tire setup you're currently using. If you get a tire/wheel set with more grip, you'll be carrying more speed and you'll need higher temp brake pads. Check them after every session as the EBC pads will start to disintegrate if they're overheated. If you see small chunks missing on the trailing edge of the pads, particularly the fronts, that's a sign they're about to come apart.
__________________
2006 Z4 3.0si Sport Package (But I'll still hang with my "homies" in the E36 forum)
Reply With Quote
  #39  
Old 06-22-2019, 12:29 AM
Rotorblade Rotorblade is offline
Registered User
Location: Bucharest
 
Join Date: Nov 2017
Posts: 94
Mein Auto: Bmw x1
Yes with slick tires you come out of the corner later, brake later and harder so much more energy to dissipate. The first day I used them, I didn't have the cooling vents and drove several laps until the liquid rbf660 boiled, and the pads lost little bits from the edge as you said. After that I didn't use the full force anymore but something like 80%. Now they have like 5mm width of material left. I suppose they need to be replaced as soon as possible

Here is a video with my car

Last edited by Rotorblade; 06-22-2019 at 12:40 AM.
Reply With Quote
  #40  
Old 06-22-2019, 10:41 PM
Andyz4 Andyz4 is online now
Officially Welcomed to the 'Fest
Location: Orlando, FL
 
Join Date: Mar 2018
Posts: 216
Mein Auto: 2006 Z4 3.0si
Good stuff. The telemetry is cool also, nice to see a sustained 1+ G in the corners.
__________________
[SIGPIC]
Reply With Quote
  #41  
Old 06-23-2019, 02:29 PM
Rotorblade Rotorblade is offline
Registered User
Location: Bucharest
 
Join Date: Nov 2017
Posts: 94
Mein Auto: Bmw x1
Quote:
Originally Posted by Andyz4 View Post
Good stuff. The telemetry is cool also, nice to see a sustained 1+ G in the corners.
Thanks, there're probably some improvements needed with weight transfer, and found some deviations from the optimal racing line.
For the telemetry I use the vbox gps which gives much more details than the phone gps. It also helps when analyzing the data with circuit_tools. But sometimes it doesn't receive good signal or the signal doesn't get validated.
Reply With Quote
Reply

See More Related BMW Stories


Forum Navigation
Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > Z Series > E85 / E86 Z4 (2003-2008)
Today's Posts Search
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On



Forum Jump


All times are GMT -7. The time now is 08:29 PM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
© 2001- VerticalScope Inc. All rights reserved.