[Max Well]

Originally Posted by GT500R

Hey Maxwell, where does the data gathering start vs. when does it end? If it takes me 3 miles until I get to the highway do I restart the trip to measure when on the highway or when I leave my driveway, then if I get off the highway am I measuring from there or when I reach my final destination when it could be 5 miles away or 1 mile away?

As my hopes for this project were to obtain reproducible data which minimizes variables as much as possible, ideally if data collection can begin once on the Interstate and cruise already set would be best. So once up to speed and cruise control on, just reset your average speed, fuel usage and odometer/trip settings to zero and take note of ambient temp. At the end of the trip (which ideally should be roughly level start and finish elevations, such as not going up a mountain pass), then record the values as shown in the spreadsheet, including ambient temp if day has warmed or cooled, and the tire pressures and temps as found in iDrive.

Many thanks for your interest in helping out, GT500R!

[GT500R]

Originally Posted by Max Well

As my hopes for this project were to obtain reproducible data which minimizes variables as much as possible, ideally if data collection can begin once on the Interstate and cruise already set would be best. So once up to speed and cruise control on, just reset your average speed, fuel usage and odometer/trip settings to zero and take note of ambient temp. At the end of the trip (which ideally should be roughly level start and finish elevations, such as not going up a mountain pass), then record the values as shown in the spreadsheet, including ambient temp if day has warmed or cooled, and the tire pressures and temps as found in iDrive.

Many thanks for your interest in helping out, GT500R!

I forgot to provide some data.

29.5 mpg
64.3 mph ave apeed
250 mile trip
4 hour 6 min
39 psi around all tires

and another trip

30.4 mpg
57.5 mph
98 mile trip
1 hour 45 min
33 psi front
36 psi rear

2018 X3 M40i
19'' rims with run flats

[DW_x3m40i]

Just completed a 1000 mile road trip but only remembered to reset the trip computer on the way back for this thread

2018 x3m40i

425 miles
6:10 h travel time
22.6 mpg
72.5 mph
698m 19" all season run flats - Bridgestone Dueler
Adaptive M suspension for the entire drive

Elevation was as high as 5000 feet at one point

Got the psi and temp after the trip ended for an hour - front r/l were 33/34 and rears were each 35 all at 61F. Temp was probably warmer during trip as outside temp was in the 90s

Also there's about 10 miles of city driving in there for a few pit stops.

[Max Well]

Appreciate the contributions by GT500R and DW_x3m40i which have now been added to the spreadsheet. Please keep the submissions coming, especially the 20" and 21" options where we only have a few lines of data. I'm thinking those sizes should have more roll friction with higher internal PSIs and temps at hwy speeds.

[Max Well]

Just getting back from another trip so have added two more rows of data. All cruise control at 79mph except for rare lane change accelerations. Interesting to see the mpg variation which, for my data at least, seems to be mainly related to atmospheric conditions, as the same route is being travelled, tire pressures cold checked immediately before departure, same fuel type and octane rating, and same vehicle load within 50lbs max.

Temperature clearly key. Still don't know where those important temp effects exert their greatest influence - higher temp producing less O2 for engine so less fuel mixed, or tire PSI increases which should decrease rolling resistance, or tire composite's friction changes at higher temps, or wind field is less dense so fluid dynamics allows easier pass-through with the G01's aerodynamics, or ...

Only takes a few seconds to record data as one nears the end of pure HWY travel legs, so if others can share their info it would be interesting to compare with the 20" and 21" options. Note my tire PSIs and internal temps are recorded at the end of our legs when the ambient temps are the highest in the stated range.

[marcusnola]

great data here.

have my m40i arriving with the 21's
didn't realize there were no all seasons available for the wheel.
anybody found all seasons for the 21's?

i live in philadelphia actually considering running these alenza's down toward the 25 degree mark then staying home on the snow days.

is this blasphemy? spending 3 grand+ on winters and swapping twice a year seems worse.

[Starz26]

Originally Posted by marcusnola

great data here.

have my m40i arriving with the 21's
didn't realize there were no all seasons available for the wheel.
anybody found all seasons for the 21's?

i live in philadelphia actually considering running these alenza's down toward the 25 degree mark then staying home on the snow days.

is this blasphemy? spending 3 grand+ on winters and swapping twice a year seems worse.

Just get aftermarket rims and a good set of winters. right around 2200 for a good set.

I would not recommend running the summers at that cold of a temperature. Also from what I have read when it get below 40 degrees F the summers do not perform well at all. Interested to hear what others have to say.

A good read: https://www.tirerack.com/tires/tiret...jsp?techid=273 - even if from a place that sells tires :O

[Old-School]

Originally Posted by marcusnola

have my m40i arriving with the 21's
didn't realize there were no all seasons available for the wheel.
anybody found all seasons for the 21's?

i live in philadelphia actually considering running these alenza's down toward the 25 degree mark then staying home on the snow days.

is this blasphemy? spending 3 grand+ on winters and swapping twice a year seems worse.

Originally Posted by Starz26

Just get aftermarket rims and a good set of winters. right around 2200 for a good set.

I would not recommend running the summers at that cold of a temperature. Also from what I have read when it get below 40 degrees F the summers do not perform well at all. Interested to hear what others have to say.

Any high performance tire will lose traction in sub 40º temps & in the 20's they will be downright greasy even on dry roads.

All season tires are not as good as either snow tires OR Summer tires, respectively - So they are a compromise in both seasons. With the 21's you are not going to have any choice but to run Summer tires so were I you I'd be getting a snow tire set. (PS; I'm also in PA & I will be you as mine is coming with 21's also - lol)

2 thoughts on a Winter set of Wheels/Tires: In the hypothetical of driving 12k per year, running a Winter set from December through March saves, in just a few years, probably one complete set of the 21" tires - so that's $2000, reducing your net cost for tires to that of the wheels. And you'll have better performance year round. I change them myself - takes about 20 minutes.

And the important thing that people seem to forget with snow tires is it's not only about going better but stopping better as well. In testing, like twice as short of a distance in snow/ice conditions. In my opinion, once you run snow tires in the winter you'll never go back.

Second thought is that I personally would buy the BMW $3k 699M Winter set. Although they are a fair bit more than aftermarket options, my opinion is that over time they won't cost any more, considering they will be infinitely more re-sellable at some point versus aftermarket wheels in the future. But whatever winter wheel you choose is entirely up to your preference..

Regardless - for me, running a Snow tire set on my X3 with our certain seasonal snow – especially when my build has the 21" combo, will be an absolute must.

[BMWGuySweden]

for us Swedes winter tires are the law. The question for is more studded or non studded winters.

[Max Well]

Originally Posted by johnparkercom

Any high performance tire will lose traction in sub 40º temps & in the 20's they will be downright greasy even on dry roads. ...

Certainly a good rule of thumb borne out from years of experience by both Consumers and the Industry I suspect. But I am curious, after collecting our data which also compares internal tire temp simultaneously with ambient temp, to what extent do higher internal tire temps from friction/travel mitigate the loss of traction issue even during low ambient temps?

I'll reference line #41 from my data chart - we drove a solid 1-1/2 hours in less than 25 degree F ambient temps, but our internal TPMS tire temp was 68 deg front, 66 deg rear (and that was at the higher cold PSI I set of 36/40 when I do higher speed Interstate travel). And I did not sense any traction issues although rarely place us in a position to need such on the Interstates. No doubt at the rec 32/35 tire PSI those internal temps would have been even higher.

I don't wish for anyone to misunderstand my question, as I am in favor of using proper caution with tires and cold temperatures. I'm just wondering if those recs take into account internal tire temp warming or whether that has any relevance at all if the exterior tire surface remains at the cold ambient temp (totally unaffected by the internal tire temp)?

[skier219]

Theoretically, summer tires won't have enough traction in very cold temps due to the rubber compound, and I have warned people about that who only think the issue is snow/ice traction. But in practice, I have run my cars down near 20F on summer tires and never noticed any dramatic change in handling. It's not like they slid off the road or couldn't provide normal braking.

Years ago someone told me that the tires would probably suck for the first couple miles in very cold weather, but get better after they warmed up. I see tires gain at least 30-40 degrees F from usage, so I suspect that gives some additional buffer.

Generally, I have only had summer tires on sports cars, which I drive less in the winter. The X3 will see year round heavy use, including drives into the mountains for skiing. I think I'll find out pretty quickly if the summer tires are a bad idea. That will be a good time to either get a seasonal set of wheels/tires or swap to all seasons. I have the 21" wheels and haven't even shopped around to know what (if anything) is available in those sizes.

[deladude]

Originally Posted by skier219

Theoretically, summer tires won't have enough traction in very cold temps due to the rubber compound, and I have warned people about that who only think the issue is snow/ice traction. But in practice, I have run my cars down near 20F on summer tires and never noticed any dramatic change in handling. It's not like they slid off the road or couldn't provide normal braking.

Years ago someone told me that the tires would probably suck for the first couple miles in very cold weather, but get better after they warmed up. I see tires gain at least 30-40 degrees F from usage, so I suspect that gives some additional buffer.

Generally, I have only had summer tires on sports cars, which I drive less in the winter. The X3 will see year round heavy use, including drives into the mountains for skiing. I think I'll find out pretty quickly if the summer tires are a bad idea. That will be a good time to either get a seasonal set of wheels/tires or swap to all seasons. I have the 21" wheels and haven't even shopped around to know what (if anything) is available in those sizes.

It really depends on the specific tire you are running and its rubber compound but I would never try to run summer tires in the winter. I used to run Khumo Ecsta XS's and they were not drivable under 45* at all. Very slick and dangerous on dry roads below mid 40s. Michelin Pilot Super Sports are not as bad in my experience but I would NEVER try to run them past mid-October (in VT).

If you know you'll be heading into the mountains in potentially snowy conditions I would reconsider your wait and see approach, why risk it? I also highly recommend a second set of wheels if you are going to run two sets of tires. Makes everything a lot easier.
Just my $0.02.

[skier219]

Yeah, I would definitely get another set of wheels if I need a second set of tires.

The place I day-trip to for skiing in Virginia is almost exclusively man made snow, so 99% of the time when I drive up there the roads are clear and dry. If they actually get natural snow I'd be more likely to drive up in my 4WD truck. Roads are not well cleared in this part of the country when it snows, and the driving can be worse than when I lived in CT and VT, believe it or not.

There was one time last year when ski conditions/weather were good and roads were clear, so I drove up in my RWD 4-series coupe (which had really aggressive summer tires, with tread pattern similar to a cue ball that would seem to be absolutely useless in snow). It wasn't until after I had pulled down into a parking area near a lift that I realized the road back out was totally covered in snow from the snow guns. They made snow all day and the road stayed about the same, so I figured it was going to be tough or impossible to get out, but the car did absolutely fine. I was really surprised that RWD with aggressive summer tires was even able to get traction much less make it up a snowy hill.

[deladude]

Nice. I suppose the average winter weather is quite different between our two states so you might be able to get away with it, esp if you have another car to use in the worst cases.

Up here single digits temps and snowy roads are pretty common and the X3 will be my only ride so I wouldn't even consider it. I'm actually looking forward to taking the M40 out in our first big storm to see how she does

[nogren]

Originally Posted by BMWGuySweden

for us Swedes winter tires are the law. The question for is more studded or non studded winters.

True. But even if it wasn't the law, I would choose (studded) winter tires during winter anyway. Actually the comfort usually gets better with the softer rubber, until it gets really cold. :-) Otherwise of course for the much better safety when stopping and cornering.
This of course with "Nordic" rubber winter tires. For European rubber, which I guess is similar to what you guys in the states get if you buy "Winter tires", the performance in winter is a bit worse. But still miles better than summer tires.

Personally I'll go for Nokian Hakkapeliitta every time!
https://www.nokiantires.com/tires/su...studded-tires/

/n

[Max Well]

Added three more lines of data, this time with our 2019 X3 M40i with Bridgestone Alenza performance RFTs (rather than Yokohama). Have also added an image of the tread differences. Would be interested in seeing similar views of some of the other Brand's offerings if anyone has a chance to share.

[skyblue2002]

Interesting read. They swapped out the 21"s for 20" OZ Hyper GT HLT wheels with Michelin Pilot Sport 4S tires and recorded significant performance gains.

https://www.motortrend.com/cars/bmw/...date-6-review/