Last post on Sep 18, 2013 at 7:28 AM
You are in the BMW Z4
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BMW Z4, Coupe, Convertible
#63 of 86 A Smoother Ride?
May 12, 2010 (2:44 pm)
I just joined this forum on the advice of a friend who owns an import repair shop. I purchased a 2005 Z-4 (probably the last "boy toy" my wife will let me have) and I just love it!!! It has every option available for this year to include the premium sport package. It rides firmer than I am accustomed-not like say; a TR-6 I had some time ago. Yes, I am a senior citizen (South of 64 yrs.) so, the question becomes what can I replace the original RFT's with to increase ride comfort to the maximum? My Z-4 has about 40k + miles and the only thing my guy tells me after he went through it before I bought it is: oil change, possibly some brake work, rotate/balance tires. All of this: "sometime this year." The tires look very good but I am told after a certain amount of time, one should consider replacement. What is available, run flat or other wise, that I should consider to get the smoothest ride?
#64 of 86 Re: A Smoother Ride? [cliff23]
May 12, 2010 (3:35 pm)
I asked a lot of questions and did a bunch of reading over a 6-month period because I could not get answers from BMW. I finally replaced the OEM tires with the same brand/model but in a newer design about a month ago. My Z4 runs a little smoother but it still does not handle the gaps and seams in the road as easily as I would like. OEM tires were Bridgestone Potenza 225/45 R17. The new tires are exactly the same except they're Generation II. BMW is putting Gen III tires on the new Z4's but said they were unable to get those shipped to the dealership yet as replacements. That may change by summer.
In the meantime, you may want to consider a non-runflat tire option. One tire dealer recommended that route if I wanted a really smooth ride. The downside is that you need to carry a can of tire inflator plus some sealant or "slime" to enable you to get to a repair shop in the event of a flat.
If you'd like, I'd be happy to share the full text of an article by an auto writer about testing runflat tires on BMW's. It's pretty interesting background and provides a glimpse of the future of runflat tires.
Let me know if I can be of more help!
#65 of 86 Re: A Smoother Ride? [steveclemens]
May 13, 2010 (5:09 pm)
Thanks Steve. I appreciate your prompt response. Of course I would be interested in you forwarding any info you have: (cliftonburrisatt.net). After your comments, I checked my tires and they are; Bridgestone Pontenza 225/40 R18, 88W. It seems from your comments I also conclude that the "seams and gaps" are less than to be desired. I also attribute this to a minor difference between hydraualic as opposed to electric operated steering. Suffice to say, I am a person who loves to drive this car when it can be done safely--not at my expense or others. These times are rare in my area.
May 14, 2010 (7:38 am)
I assume from your note that you have hydraulic steering on your '06 Z4, is that correct? The electronic steering on my '07 Z4 may be a contributing factor to the tramlining I experience. BMW seems to be going electronic on many components to provide more feedback to the driver and more precise control. But as a real amateur about these things, that may also mean more feedback than I really want.
In response to my handling concerns, the dealer performed several alignment checks & adjustments. They also re-calibrated something called the steering angle sensor. Apparently this is another electronic device that constantly monitors the direction in which the front wheels are pointing. Again more feedback to the steering wheel.
I will send you a copy of the 3G runflat article directly to your email address along with a couple of additional comments so we can avoid doing all this sign-in stuff.
Have fun with your new toy, especially now that spring is here--at least it's supposed to be. We had a good shot of snow here in Denver two days ago but it may finally warm up enough this weekend to get our tomato plants in the ground!
#67 of 86 Re: RunFlat Tire Info [steveclemens]
May 26, 2010 (1:39 pm)
If you don't mind, I'd very much appreciate getting a copy of that article as well. Please send it to curethebluesaol.com. Thanks!
#68 of 86 Re: RunFlat Tire Info [steveclemens]
by Claire@Edmunds HOST
May 26, 2010 (3:39 pm)
It would be great if you could share the info right here in the forums too -- I'm guessing a lot of people would be interested.
Automotive News & Views | Coupes & Convertibles
#69 of 86 Re: RunFlat Tire Info [claires]
May 26, 2010 (5:46 pm)
Here's the article I found on the web that finally enabled me to convince my BMW dealer that newer runflat tires might help eliminate the tramlining problem I was having. It helped so much that between BMW and the dealer they picked up 2/3 of the cost of four new Bridgestone RunFlats for my car.
Bridgestone 3G RFT Tires take the shock out of run-flats
by Michael Harley on Jul 6th 2009
Compared to a conventional tire, the construction of a self-supporting run-flat requires additional material thickness in the sidewalls to prevent the tire's collapse once it has lost pressure. It is this additional reinforcement that adds weight, reduces ride comfort, and increases rolling resistance (these characteristics are the kiss-of-death to performance).
Consumers embraced the additional mobility and safety benefits of the 2G RFT, but they never warmed to the handling compromises as a result of the additional unsprung weight, the harsh ride (the sidewalls are a noticeable 15 percent harder than a conventional tire, says Bridgestone), or the expensive replacement cost (up to 30 percent higher, in some cases). Frustrated, many vehicle owners exchanged their run-flat tires with conventional tires even before it was time for their replacement.
Bridgestone research and prowess resulted in three new cutting-edge technologies:
Unique ply construction: The reinforcing layers of a tire are called the "ply." Bridgestone developed a tire ply that uses the heat generated by a deflated tire to contract and curb deformation. In simple terms, the material in the new sidewalls automatically shrinks to abate damage from abrasion and heat. When the tire cools, the ply automatically returns to its original state.
New rubber compounds: Laboratory-engineered rubber compounds, Bridgestone calls them "NanoPro-Tech," are also used in the sidewalls to limit heat. Conventional tire compounds warm through friction between the carbon and polymers (two common tire ingredients). By optimally distributing the polymers, friction and heat are minimized.
Innovative heat control: Bridgestone developed so-called "cooling fin" technology for the new tire. Molded into the sidewall are small protrusions (think of them as miniature spoilers). While this seems rather rudimentary, they effectively disrupt the airflow at the surface to help radiate heat and cool the tire.
Bridgestone encouraged us to try its new third-generation run-flat (3G RFT) from behind the wheel. Strapped in near identical late-model BMW 5 Series vehicles, Bridgestone offered us the opportunity to drive three variants of its high-performance RE050A tire: Conventional, 2G RFT, and 3G RFT.
We drove the conventional RE050A first. A high-performance tire fitted to such cars as the Nissan 370Z and Lexus IS-F, the standard rubber was comfortable on the smooth sections. The course/rough pavements didn't provide much of a challenge either as the compliant sidewalls absorbed the abuse without drama.
Next, we tried a set of RE050A "2G" run-flats. While they were comfortable on the smooth sections, the compromises of the 2G run-flats were immediately evident when we entered the first sections of rough pavement. What had been damped by shock-absorbing sidewalls on the standard tires was now transferred into the cabin in the form of sharp, and rather uncomfortable, impacts. This test reinforced what many owners have expressed and what we have personally experienced.
The final run through the test course was done with the all-new RE050A "3G" run-flats. Eureka! Surprising even the skeptics among us, the third-generation tires were nearly imperceptible in ride quality from the standard tires (non run-flat) we had driven on merely minutes earlier. The ride was very comfortable. According to Bridgestone, test instruments reveal that the slight difference in ride quality was a near-imperceptible 5 percent change in harshness.
Another fleet of late-model BMW 5 Series vehicles were fitted with 2G RFT and 3G RFT tires for back-to-back comparisons. The roads were in fairly lousy condition, but they again demonstrated the newfound compliance one can expect with the third-generation run-flat.
The track sessions and test drives made it clear that Bridgestone has eliminated the biggest objection to run-flat tires – abusive ride quality. We never had an opportunity to push the performance envelope of the tire, but Bridgestone says the tread compound of the RE050A 3G RFT is identical to that on the conventional tire, so the grip levels should be very high.
But wait, there's more to the story:
There are two "However's" and one "Therefore" to add to my post. However #1: The dealer could not get their hands on 3G RunFlats, even though the factory is currently delivering 2010 Z4's with them installed. So they installed 2G's all around on my Z4. However #2: The 2G's did not make a noticeable improvement in handling.
Therefore #1: After driving on the 2G's for a month and finding the Z4 still incredibly difficult to handle, I traded it in and bought a new Lexus IS 250C. After three very frustrating years of coping with "superior German engineering" that never translated into an enjoyable driving experience, I'm now a very happy man. Plus I now have two more seats, a slick convertible hardtop and a ton of goodies that actually make driving fun--for the about the same $$.
I hope others have better success . . .
#70 of 86 Snow tires plus Wheels
Jul 31, 2010 (9:39 am)
Please give me advice about snow tires and wheels for a Z4. Just thinking of buying the snow tires and not the wheels.What do you think?
Looking to buy '08. Plan to buy the Blizzak tires. I am on a budget
#71 of 86 Z4 tire wear
Jan 12, 2011 (10:02 am)
I have a 2007 BMW Z4. I wanted a six-speed so I got a 3.0i with the sports package. Probably should have done my homework a bit better. I bought the vehicle used (after having driven and loved my BMW Z3 for ten years and 130,000 miles). I was not aware that the car has different size tires on the front and the rear so they can't be rotated. I don't know what genius of German engineering decided this was a good idea. (Yea, I know it is about performance and handling, but practicality should enter into the equation somewhere.) Between the fact that the tires can't be rotated and the negative camber, the rear tires wear out in 10,000 miles, with more wear on the inside than the outside. It is my understanding that the inability to rotate them and the uneven wear voids any mileage warranties that come with the tires. I have received a suggestion to use Michelin Pilot Sport A4 Plus tires on it. However, if all of the tires are going to wear out in the same amount of time (and the warranty will not be valid) I would rather go with something cheaper. Any experiences or advice you can share?
#72 of 86 Re: Z4 tire wear [z4lady]
Jan 13, 2011 (8:47 am)
I believe all factory Z4's have the same size front and rear wheels.
The 2007 Z4 came with 17 x 8.0 in. wheels with 225/45R W tires.
If you you have different sizes, they are courtesy of the person you bought your car from.