Tirerack
Use the following links to go directly to useful tirerack winter items: Tirerack Winter Tires. Gary's Winter Tire FAQ.
Using the links directly supports E90Post with tirerack sales commision!

  E90Post
 


TireRack

   PLEASE HELP SUPPORT E90POST BY DOING YOUR TIRERACK SHOPPING FROM THIS BANNER, THANKS!
 
BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Wheels and Tires Forum Sponsored by The Tire Rack > Changing RFT at home?



Wheels and Tires forum Sponsored by The Tire Rack
Please help to directly support e90post by doing your tirerack shopping from the above link. For every sale made through the link, e90post gets sponsor support to keep the site alive. Disclaimer

Reply
 
Thread Tools Search this Thread
      10-10-2013, 01:58 AM   #45
garyhgaryh
Major
garyhgaryh's Avatar
United_States
25
Rep
1,208
Posts

 
Drives: Supercharged e30 M3
Join Date: Jan 2007
Location: santa cruz

iTrader: (4)

Quote:
Originally Posted by driverman View Post
Changing low profile tires can be challenging, but changing low profile RFTs is even more challenging because the sidewalls are very stiff.

There are lots of threads on this forum about wheels being damaged by the bar they use to separate the tire bead from the wheel. It happened to me - 3 out of 4 wheels damaged by a seasoned veteran with good equipment. He wasn't careful enough.

Recommend you look for a good shop with good equipment and reasonable prices and have them do it.
I expect that I'll scratch the rims so if it happens, no big deal. If I don't I'll be stoked .
Appreciate 0
      10-10-2013, 12:15 PM   #46
white_light
Enlisted Member
0
Rep
44
Posts

 
Drives: 2011 e92
Join Date: Sep 2013
Location: new jersey

iTrader: (0)

i wouldnt recommend..
Appreciate 0
      10-10-2013, 01:29 PM   #47
MandMs335Msport
Private First Class
MandMs335Msport's Avatar
1
Rep
131
Posts

 
Drives: 335i M-sport, '10, etc
Join Date: Feb 2013
Location: San Luis Obispo County, CA

iTrader: (0)

Well, not sure where this is going, but its interesting. Did the OP buy a nice spin balancer too? Around here its $20, about 10 shops within 10 miles too, and I'm kind of in the country. I guess if I was in the middle of Texas and 50 miles from a real town, it might be a different story.
Appreciate 0
      11-04-2013, 01:20 AM   #48
garyhgaryh
Major
garyhgaryh's Avatar
United_States
25
Rep
1,208
Posts

 
Drives: Supercharged e30 M3
Join Date: Jan 2007
Location: santa cruz

iTrader: (4)

Well, I'm not sure if the original poster monitors this thread or if anyone cares, but I was able to successfully change out my stock RFTs yesterday. I thought about this for weeks and it was easier than expected. The sidewalls are so stiff I bent a tire iron, but it's not as crazy as it seems and you do not need a 28k tire machine that is used by the bmw dealer or an off brand $4-5k RFT tire changer.

So for the record, someone has changed RFT at home on this forum.
Attached is a picture of my original RFT (left rear-1st picture). I wore it down to the cord. Anyone know why my left rear would wear much faster than my right rear (2nd picture)?
I think perhaps I weight down the left side and am usually the only passenger 90% of the time.

I'll post a video of the runflat replacement if anyone is interested.
Gary
Attached Images
  

Last edited by garyhgaryh; 11-04-2013 at 03:04 PM.
Appreciate 0
      11-04-2013, 09:36 AM   #49
driverman
Captain
United_States
8
Rep
604
Posts

 
Drives: 2008 E90 328i 6MT
Join Date: Nov 2008
Location: Sacramento, CA

iTrader: (0)

Gary:

Congratulations. You proved it can be done. Did your wheels come out unscathed? If so, even more congratulations. I'd like to see the video if you don't mind posting it.

The uneven tire wear in the back was most likely caused by out-of-spec alignment. Recommend you get a 4 wheel alignment.
Appreciate 0
      11-04-2013, 02:29 PM   #50
garyhgaryh
Major
garyhgaryh's Avatar
United_States
25
Rep
1,208
Posts

 
Drives: Supercharged e30 M3
Join Date: Jan 2007
Location: santa cruz

iTrader: (4)

Quote:
Originally Posted by driverman View Post
Gary:

Congratulations. You proved it can be done. Did your wheels come out unscathed? If so, even more congratulations. I'd like to see the video if you don't mind posting it.

The uneven tire wear in the back was most likely caused by out-of-spec alignment. Recommend you get a 4 wheel alignment.
Thanks Driverman.

The rims came out unscathed! Remarkable, even though I used vice grips .

Here is the video. Let me know what you think:



Gary
Appreciate 0
      11-04-2013, 04:10 PM   #51
driverman
Captain
United_States
8
Rep
604
Posts

 
Drives: 2008 E90 328i 6MT
Join Date: Nov 2008
Location: Sacramento, CA

iTrader: (0)

Gary:

Great job! Very impressive. Thanks for posting.

I had a guy unmount my RFTs and he had the right equipment. He damaged 3 of the 4 rims!

51 psi sounds high.
Appreciate 0
      11-04-2013, 05:52 PM   #52
garyhgaryh
Major
garyhgaryh's Avatar
United_States
25
Rep
1,208
Posts

 
Drives: Supercharged e30 M3
Join Date: Jan 2007
Location: santa cruz

iTrader: (4)

Quote:
Originally Posted by driverman View Post
Gary:

Great job! Very impressive. Thanks for posting.

I had a guy unmount my RFTs and he had the right equipment. He damaged 3 of the 4 rims!

51 psi sounds high.
Driverman:

Thank you for the feedback, I appreciate it.

As you can see, I took it a step at a time and since it was my rims and my machine, I was being very careful (esp since I didn' t know if my machine
was durable enough to handle the stiff sidewalls of RFT). The only thing I noticed when reviewing the video was that when I mounted the new tire, I put the bead of the tire across the sensor. I didn't realize I did that until I saw the video at 11:44. I could have broken my sensors, but luckily that did not happen.

I bet the guy who unmounted your runflats was nervous you were watching (assuming you were watching him). I make alot of mistakes when I know I'm being examined under a microscope.

About the 51 psi inflation pressure, I always pump my tires to max to get the best mileage. What pressure do you use?

Gary
Appreciate 0
      11-04-2013, 06:19 PM   #53
driverman
Captain
United_States
8
Rep
604
Posts

 
Drives: 2008 E90 328i 6MT
Join Date: Nov 2008
Location: Sacramento, CA

iTrader: (0)

Quote:
Originally Posted by garyhgaryh View Post
Driverman:

Thank you for the feedback, I appreciate it.

As you can see, I took it a step at a time and since it was my rims and my machine, I was being very careful (esp since I didn' t know if my machine
was durable enough to handle the stiff sidewalls of RFT). The only thing I noticed when reviewing the video was that when I mounted the new tire, I put the bead of the tire across the sensor. I didn't realize I did that until I saw the video at 11:44. I could have broken my sensors, but luckily that did not happen.

I bet the guy who unmounted your runflats was nervous you were watching (assuming you were watching him). I make alot of mistakes when I know I'm being examined under a microscope.

About the 51 psi inflation pressure, I always pump my tires to max to get the best mileage. What pressure do you use?

Gary
I didn't watch the guy unmount my RFTs as a courtesy to him. But I looked at the new tires mounted on the same rims and saw the damage before he took the car off the rack. I pointed it out immediately and he tried to worm out of it. He had great equipment and over 20 years experience but wasn't careful enough. That's why I appreciate what you did with less equipment.

I used the recommended tire pressures plus 2 psi. In my case (E90, 328, sports package, under 100 mph), the recommended pressure is 32 psi all around. So I run about 34.

I experimented with tire pressures ranging from 32 to 40 until I found the balance I liked, keeping a bias towards what BMW recommends. As tire pressures increased, so did harshness on rough roads.

BMW selects these pressures to strike a balance between ride, gas mileage, handling, traction, braking, safety and who knows what else. They probably run all their handling, braking and traction control tests with those pressures.

How do tires at 35 psi perform compared to tires at 50 psi? I would guess that tires inflated to 50 would provide better steering response and more of that wonderful "planted" feeling, but they probably won't hold the road as well on turns (something to do with slip angle?). How about braking? I don't understand the factors that go into handling and braking. It would be great if a tire engineer or someone from tirerack chimed in on the performance and safety ramifications of running tires at maximum pressure all the time.

Here's a good description of max tire pressure from tirerack:

http://www.tirerack.com/tires/tirete...jsp?techid=196
Appreciate 0
      11-04-2013, 07:37 PM   #54
garyhgaryh
Major
garyhgaryh's Avatar
United_States
25
Rep
1,208
Posts

 
Drives: Supercharged e30 M3
Join Date: Jan 2007
Location: santa cruz

iTrader: (4)

Quote:
Originally Posted by driverman View Post
I didn't watch the guy unmount my RFTs as a courtesy to him. But I looked at the new tires mounted on the same rims and saw the damage before he took the car off the rack. I pointed it out immediately and he tried to worm out of it. He had great equipment and over 20 years experience but wasn't careful enough. That's why I appreciate what you did with less equipment.

I used the recommended tire pressures plus 2 psi. In my case (E90, 328, sports package, under 100 mph), the recommended pressure is 32 psi all around. So I run about 34.

I experimented with tire pressures ranging from 32 to 40 until I found the balance I liked, keeping a bias towards what BMW recommends. As tire pressures increased, so did harshness on rough roads.

BMW selects these pressures to strike a balance between ride, gas mileage, handling, traction, braking, safety and who knows what else. They probably run all their handling, braking and traction control tests with those pressures.

How do tires at 35 psi perform compared to tires at 50 psi? I would guess that tires inflated to 50 would provide better steering response and more of that wonderful "planted" feeling, but they probably won't hold the road as well on turns (something to do with slip angle?). How about braking? I don't understand the factors that go into handling and braking. It would be great if a tire engineer or someone from tirerack chimed in on the performance and safety ramifications of running tires at maximum pressure all the time.

Here's a good description of max tire pressure from tirerack:

http://www.tirerack.com/tires/tirete...jsp?techid=196
Driverman:

Your post got me thinking that perhaps I should rethink how high I should inflate my tires.

I drive alot so I aim to get the best possible mileage (I also have a Honda VX and I pump it up to the max of 44psi).

When I'm autocrossing or drag racing, I inflate to what is appropriate. For example, on my supra, I will deflate the rears to 20-25 psi for traction.

Even on my road and mountain bikes, I pump to the max psi, but I notice some obvious things:
1. At high psi, I can go faster with less effort
2. On my mountain bike, I lose traction at high psi on very very steep grades (22+%).

Basically what I'm saying is that I pump to max psi in all cars to get good fuel economy and great handling/responsiveness, but I know I'm losing some traction at extremes.

Your post makes me rethink this. I also found the following (see attachment) which is published inflation pressure.

I also don't check my pressure that often so if I lose some air, having it at max pressure will usually give me a buffer so if I do lose air, I'm usually still above the ideal or recommend pressure of, say, 32psi.

I never, ever had an issue with running at max psi, but I wonder if my tire wear in my previous post was caused by too much tire pressure?

Thanks for the tirerack link. I use them alot for my resources.

One thing I noticed after switching from Michelin Pilot Sport to Bridgestones RFTs. I like the Michelin's more. The Bridgestone is not as responsive and feels vague.

Anyone know why some 335i come with Michelin Pilot Sport RFT and others come with Bridgestone RFT? The Michelin's came with my '08 sport package when I ordered the car.

Speaking of these tires, both of these brands recently have rebates.
For those of you mounting your own tire, keep this in mind. With the Bridgestone rebates, if you mount your own tires, you will have invalidated your rebate since they require proof of mounting from a "legit" shop.
When I mounted new tires on my wife's car, we could not get the rebate.

I looked at the Michelin Rebates last night and read the fine print and they have no such restriction.


Gary
Attached Images
 
Appreciate 0
      11-04-2013, 09:21 PM   #55
driverman
Captain
United_States
8
Rep
604
Posts

 
Drives: 2008 E90 328i 6MT
Join Date: Nov 2008
Location: Sacramento, CA

iTrader: (0)

Assuming you have the sports package and 18" wheels and drive under 100 mph most of the time, BMW recommends 32/38. The difference between front and back affect understeer/oversteer. So if I were you, I'd try 35/41 for a while. It would be interesting to see how that affects your gas mileage and the overall feel of your car.

I haven't been to Santa Cruz for a while so I don't know how smooth the roads are, but if they are rough, you should enjoy a much better ride.

You got me thinking about max pressure. It might be good for one of us to start a new thread on the pros and cons of running your tires at max pressure. Hopefully, a few experts would chime in.
Appreciate 0
      11-05-2013, 12:31 PM   #56
garyhgaryh
Major
garyhgaryh's Avatar
United_States
25
Rep
1,208
Posts

 
Drives: Supercharged e30 M3
Join Date: Jan 2007
Location: santa cruz

iTrader: (4)

Yes we should start another thread about this if we continue since it ruins this thread great thread about changing RFTs.

Driverman - thanks for your input. I may try 35/41. Currently everything is at max for my commute to work.
Appreciate 0
      11-05-2013, 12:56 PM   #57
Tom K.
Major General
Tom K.'s Avatar
United_States
54
Rep
5,409
Posts

 
Drives: '07 328iT, '13 Boxster
Join Date: Mar 2008
Location: Maryland

iTrader: (0)

Quote:
Originally Posted by garyhgaryh View Post
Well, I'm not sure if the original poster monitors this thread ...
Gary
Hit and run. The OP has posted nothing to e90post since #9 in this thread back in Dec., 2012.

Tom
Appreciate 0
      11-06-2013, 05:08 AM   #58
garyhgaryh
Major
garyhgaryh's Avatar
United_States
25
Rep
1,208
Posts

 
Drives: Supercharged e30 M3
Join Date: Jan 2007
Location: santa cruz

iTrader: (4)

Quote:
Originally Posted by Tom K. View Post
Hit and run. The OP has posted nothing to e90post since #9 in this thread back in Dec., 2012.

Tom
Thanks Tom. Hope he sees this thread someday.
Appreciate 0
Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 Off
Forum Jump


All times are GMT -5. The time now is 01:22 AM.




e90post
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST