Wheels and tires dilemma....

[Z4Rick]

Ok. So I have this new Z, and I am learning all I can about some of its state of the art features. One such item I am woefully under-informed on is wheels and tires. I know little about 'low profile' tires - and even less about 'run-flats'. I DO know that tire choice has a HUGE impact on performance in these machines and am not willing to compromise much in that regard.

Having said that, here is my quandary...
I live in the mountains of western Maryland - the Appalachians. They are not the Rockies, but at 3,000 feet ASL, they are not just hills either. The physical location just 100 miles or so from the east coast and their north\south orientation makes them an "Eastern Continental Divide" and the highest ridges east of the Great Plains and, ultimately, the Rockies. This allows for some serious weather to build in the plains and slam into the ridges around me which help scrub out precipitation before those storms head downhill to warmer elevations and eventually, the Atlantic coast. We get about 240" of snow every year from November thru early April, (I live 3 miles form a ski resort!) and commonly will see snowfalls of 6" to 12" most every other week or so. I often have to plow my driveway with an ATV on a daily basis to clear 3" or more for 30 to 40 days at a stretch in January and February.

So, I either leave the Z in the garage, or get a set of snow tires. If I am going to get snow tires, I might as well get a new set of wheels to make changing them back and forth easier. My "summer" tires are the Potenzas the car came with and are mounted on 17" wheels. Bear in mind we own two very capable 4X4 vehicles and will NOT be using the Z for a commuter. I expect to not use it that much at all frankly, but would like the option to, and might easily be forced to drive in storms when returning from trips "downstate"...

My questions:
If I am going to get new wheels, do I go for 18", (or 19") instead of the 17's? (I do like the look of the 18's better on the Z than the 17's....)

Other than cosmetics, is there any good reason to expect a performance, or 'ride' quality, advantage/disadvantage to going to a larger wheel?

Should I use the larger wheels for my summer or winter tires?

You Brits see snow - what brand snow\wet weather tire would you recommend? (I lean towards Bridgestone Blizzacks, but am willing to learn....)

Do you use the same tires on the front too? (I am guessing "Yes"....)

Do you "rotate" them?

What is the current preferred brand of "Summer" performance tire? (The Michelin PSS might be a choice I'd make depending on availability...)

Are there other considerations I have missed?

In advance, I truly appreciate any advice you all might have.....

 

[Grumpyowl]

Our wheel and tyre expert Mr Wilks will be along shortly.

Yes we get snow in GB but rarely experience what you get.
On mainland Europe some countries Germany for instance I believe (I might be wrong which is not unusual)
It's law to run with winter or all season tyres for so many months of the year.

Here in GB there is no such law and the majority just run all year round on the same tyres.
My DD for the last 30 + years has been a company owned car doing 30-40k miles a year, I've never changed for or used winter tyres,very occasionally I've used snow chains to get back home but they are a pain to use so they're stashed away in the garage somewhere.
It would be very unusual if I couldn't use the car for more than 3-4 days because of snow.
So the company don't want the expense and I don't bother.

Here in Derbyshire we have a famous road that cuts over from Sheffield to Manchester the snake pass we'd call it a mountain you'd call it a large Hill
It was closed yesterday 29th April due to snow but you find another route.

Winter tyres are becoming more popular but with heavy taxes here a lot can't or don't want to afford the luxury of 2 sets of wheels and tyres.

The compromise on new summer wheels for comfort style and performance would probably be 18 inch rims.

The experts will be along soon Rick.

 

[The_Dude]

With that much snow possible I'd stick the z in the drive and get the Dodge Ram out

In all seriousness as said above we rarely get serious snow here...3cm is enough to cause travel chaos! But saying that I still put winters on as its not just for snow, but lower temps. Mine are on 17" rims and I have blizzacks on the front and hankooks on the rear, no other reason than the garage only had them on when I went to replace them. Both seem to grip well but I think the Bridgestone had the edge.


My normal wheels are 18 with Michelin all round. Love em. I'd keep the larger diameter for summer and keep the 17 for your winter.

 

[mr wilks]

Id either stick some winters on the 17s for that crisp winter drive or most likely flog the 17s for what you can & go deep into some 19s
Ive just swapped from 18s on runflat Bridgestones to 19s on non runflat Contis & no downside to ride quality whatsoever
The E89s arches can easilly take 19s & no need to go skimpy on the rubber :roll:
These are on 255 35 19 rears / 225 40 19 fronts ( probably switch to 235 40 when i find some )
Speedo checked against TomTom is more accurate now than on OEM set up :wink:

 

[Z4Rick]

Id either stick some winters on the 17s for that crisp winter drive or most likely flog the 17s for what you can & go deep into some 19s
Ive just swapped from 18s on runflat Bridgestones to 19s on non runflat Contis & no downside to ride quality whatsoever
The E89s arches can easilly take 19s & no need to go skimpy on the rubber :roll:
These are on 255 35 19 rears / 225 40 19 fronts ( probably switch to 235 40 when i find some )
Speedo checked against TomTom is more accurate now than on OEM set up :wink:

NICE wheels! I do like the 'look' of 19's, but I seem to have more tire selection with 18's on Tirerack.com...more wheel choices too. Gotta have runflats though - I'll be doing some desert trips out in the Southwest and don't relish a blowout 80 miles from nowhere!

 

[Z4Rick]

With that much snow possible I'd stick the z in the drive and get the Dodge Ram out

In all seriousness as said above we rarely get serious snow here...3cm is enough to cause travel chaos! But saying that I still put winters on as its not just for snow, but lower temps. Mine are on 17" rims and I have blizzacks on the front and hankooks on the rear, no other reason than the garage only had them on when I went to replace them. Both seem to grip well but I think the Bridgestone had the edge.


My normal wheels are 18 with Michelin all round. Love em. I'd keep the larger diameter for summer and keep the 17 for your winter.

I think the 17s I have will end up with snow tires and new summer rubber will have new wheels - probably 18s. I have Hankook MTs on my FJ Cruiser - great winter treads! The Blizzack is my likely choice for the Z - assuming I can find run flats... Thanks!

 

[Z4Rick]

mr wilks - a question, if you have a second....
Does a 19" wheel and tire reduce unsprung weight enough so that it might have an effect on a stock suspension? I ask because a salesman at BMW told me the 19" wheel option is only available on cars with the 'adaptive suspension' package - which suggests a different spring/shock setup????

 

[R.E92]

19" will probably increase the unsprung weight.

My opinion would be to stick with 18" wheels. 19s look nice but you sacrifice on comfort. Also more chance of a bent wheel with the lower sidewall.

 

[Z4Rick]

" Also more chance of a bent wheel with the lower sidewall."

YES! I had forgotten this! - and a bigger concern for me than most - I have a history of 'finding' pot holes by feel!

 

[extaz]

Just wanted to point you to a great tire link: http://www.tirerack.com/tires/reviews/MenuServlet?search=surveyComments
I have limited experience with E89 tires but have heard strong opinions regarding 19" wheels causing unacceptable hard ride and tramlining, especially with runflats.
Also: Summer tires get tricky at temps under 45 degrees which in the mountains can easily be arrived at as you climb.
A very good runflat All Season is the Bridgestone Duralast. Check out the reviews, and the wear rating is very good. These forums are very negative about runflats but I think they are getting better.
My personal take is that I would be happy with the 17" for all around use especially in bad weather. The ride is much better, and they are less apt to blow out from a pothole at 80mph as happened once to me right on RT 95. IMHO big tires and wheels are as much for appearances as anything. I tracked and autocrossed (years ago) on 16" and 17" tires. The contact patch is the same. (Google it). Just another perspective.
Hope you are enjoying your learning curve with the E89.

 

[Z4Rick]

Just wanted to point you to a great tire link: http://www.tirerack.com/tires/reviews/MenuServlet?search=surveyComments
I have limited experience with E89 tires but have heard strong opinions regarding 19" wheels causing unacceptable hard ride and tramlining, especially with runflats.
Also: Summer tires get tricky at temps under 45 degrees which in the mountains can easily be arrived at as you climb.
A very good runflat All Season is the Bridgestone Duralast. Check out the reviews, and the wear rating is very good. These forums are very negative about runflats but I think they are getting better.
My personal take is that I would be happy with the 17" for all around use especially in bad weather. The ride is much better, and they are less apt to blow out from a pothole at 80mph as happened once to me right on RT 95. IMHO big tires and wheels are as much for appearances as anything. I tracked and autocrossed (years ago) on 16" and 17" tires. The contact patch is the same. (Google it). Just another perspective.
Hope you are enjoying your learning curve with the E89.

More good input ...I am grateful!

Its beginning to look like a new set of wheels - either 17 or 18 and "summer tires", and the existing 17" wheels with snow/wet treads. I've got time, so we'll see what we see.

And yeah, I'm having a blast! I climbed a very long hill today with some pretty good shifts - I had no idea that exhaust sounded THAT good. Best car I ever owned. Time of my life!

Thanks!

 

[Mr Tidy]

Glad you are enjoying your Z4!

I'll be honest I wouldn't use my Z4 in snow as I've got a 325ti Compact as a daily that now has a set of Michelin Alpin winter tyres - which is no doubt the reason we had such a mild winter just gone! :lol:

 

[Z4Rick]

Glad you are enjoying your Z4!

I'll be honest I wouldn't use my Z4 in snow as I've got a 325ti Compact as a daily that now has a set of Michelin Alpin winter tyres - which is no doubt the reason we had such a mild winter just gone! :lol:

I do not disagree! I actually have 2 very capable 4WD vehicles for the Mrs. and I specifically for the winter months. However, i will go ahead with a set of winter/wet treads on the stock 17's for two reasons. First, the cold season. It lasts from early November to late April, so for 6 months of the year I have temps at, or below 45 Degrees (F), (7degrees C). By corollary, I have another 6 months with warmer temps. I like the Z way to much to leave it in the garage for 6 mos. unused! Second reason is unpredictability. I have left here many days in 50 degree (10C)) sunshine only to drive home later in the day thru horizontal snow, 4" deep and building, and 15 degree temps, (-9C) Such is life in the mountains! (Also why I probably own the only Z4 in this county!)

An interesting article that supports the suggestion a number of you have made about using my 17' wheels for winter treads:
http://www.tirerack.com/winter/tech/techpage.jsp?techid=126

 

[Spuffington]

I'll be sourcing a nice set of 17s for my Zed once I get over the initial cost of buying it.

My Job is split between London and Frankfurt and have worked in Germany for many years, on and off and there you see the positive effects winter tyres have in order to keep roads moving in even the most severe winters. But also in mild ones too. In general, once you have winter tyres on a vehicle, your biggest limitation is actually the height of the front spoiler during snow. Winter tyres are invaluable to me - whether it rains or snows, I at least know I've given myself the best opportunity for stopping and sticking to the road that I can do - keeping my family safe in the family wagon and helping me get to the Station in the mornings without incident. I have fitted them every winter, to every car in my fleet for the last 10years and don't regret it a jot.

Winter tyre haters will either say they've got by for years without and never struggled, or will try and point fingers at winter tyre users as reckless and looking to exceed safe limits in bad weather. Both opinions IMO are baseless - empirical evidence is there to support much shorter stopping distances in both wet and cold weather as well as in snow and ice when compared with summer tyres and just because you have them fitted, doesn't mean I don't drive to the conditions. In actual fact, I've given myself DOUBLE the safety envelope.

Best practice is to switch onto the smallest rim on the manufacturers doorcard and run the narrowest and high profile tyres you can (again, usually signalled on the doorcard). On my 23i, it's 17". BMW have been running good offers on OEM sets so may go down that route with the Zed.

With my other vehicles I have always sourced my wheels from eBay - in the UK smaller wheels are frowned upon so certainly used to get sold on cheaply; less so these days as people have woken up more to the merits of winter tyres. And then I would fit the OEM winter rubber shown on realoem for that vehicle to those rims. If they're a square setup (i.e. same size tyres & rims front & back) then I would swap front & rears each winter to keep the wear even. Winter tyres are less effective below 4mm tread depth, although some people run them into spring in order to get maximum wear out of them before binning them.

In Germany the phrase is "O bis O" or rather explained a bit further "Oktober bis Ostern" - October to Easter, although many have been caught out this year due to early Easter and a cold snap in early April. But common sense should apply and daily temps look either less than 7degs C for any period of time going into winter, this is usually the sign to get them on and same in reverse in April-time.

Hope that helps a little?

 

[Z4Rick]

Yes it does. It verifies everything I have learned so far. Funny, but as I read your post, I received the following weather maps from a weather service I subscribe to. It seems a late push of cold air will be bringing SNOW to the western mountains of the East Coast this weekend as it passes over the Great Lakes:
The point of that blue arrow is about 1 mm from my front door!

The point of the text bubble is about 2 mm from my back door!
I will be at my niece's wedding Sunday evening in Washington, D.C. and driving home about 8:00PM thru those "Lake Effect Snows", (which can be quite nasty.)

THIS is why I need snow treads!
Just lovely. Guess I drive the Toyota to the wedding!