[blinsc]

Originally Posted by AGONXF30

As asked above, what is the MPH impact on this set up. The 275/40R21 and 315/35R21 are nearly identical in diameter, but the 275/45R21 and 315/40R21 are a bit off, not by much.

You can use this site to calculate all that info and more. Click on the Tire Comparison tab.

https://tiresize.com/calculator/

For the above example, OEM is 275/40/21 and upsize is 275/45/21.

Speed would be 31/62/93 mph when speedometer read 30/60/90 mph.

[AGONXF30]

Originally Posted by blinsc

You can use this site to calculate all that info and more. Click on the Tire Comparison tab.

https://tiresize.com/calculator/

For the above example, OEM is 275/40/21 and upsize is 275/45/21.

Speed would be 31/62/93 mph when speedometer read 30/60/90 mph.

But what is YOUR experience. For example, waze has a GPS speed, which shows my F30 speedo is off by 3-4 MPH (faster). My G05 is pretty spot on. GPS steady state speed calcualtions are pretty accurate. Another example is going by those temporary RADARs that read the speed, F30 is usually off, G05 is spot on. So my question is what have your experience been going up one sidewall size?

[mnx5er]

To have more options, I am considering going square with the 275/40R21 tires all around using the stock 21" rims. It appears those tires will fit the rear rims and would not impact iDrive or the speedometer. I think....

[915M]

Originally Posted by walkday

If you have decided on all-season tires, the best option is to go up one size. I put on Michelin Primacy Tour A/S 315/40 rear and 275/45 front on my 741m staggered rims. No rubbing even on the lowest air suspension setting. They are not run-flats, so I also added a good tire kit in the trunk for minor repairs. The 45e doesn't have space for a spare tire.

Do you have more pictures to share?

[hufington]

Originally Posted by ST3

Get a second set of wheels ( 19 or 20in) and dedicated snow tires (more for operating temps than actual snow).

+1 On this.
It is easier to swap a wheel set than two sets of tires on one set of wheels. No need to balance, adjust the sensors, etc. Later, you can sell the winter set or keep it for the next vehicle. In the end, it'll be more convenient and cheaper.

[10101X5]

Don’t search by cars. Search by size. I was in this situation and thought they didn’t make many non RF. They do. I got Michellin Pilot Sport All Seasons 21” staggered and they are wonderful. Drive like a different car.

[slicky]

Originally Posted by 10101X5

Don’t search by cars. Search by size. I was in this situation and thought they didn’t make many non RF. They do. I got Michellin Pilot Sport All Seasons 21” staggered and they are wonderful. Drive like a different car.

Ps4 are not available in a matching staggered size. What sizes are you using?

[AGONXF30]

Originally Posted by 10101X5

Don’t search by cars. Search by size. I was in this situation and thought they didn’t make many non RF. They do. I got Michellin Pilot Sport All Seasons 21” staggered and they are wonderful. Drive like a different car.

Pilot Sport AS4 aren’t available in 275/40R21 315/35R21. I have looked as they are my favorite all season tire and a hell of tire.

[10101X5]

I just looked at what I got again. I got PS AS4 for fronts and PS 4 for the rears. I must have overlooked 4 for all seasons. Lol. My stock P Zero RF is also Summer tires. So I guess I'm OK.

[AGONXF30]

Originally Posted by 10101X5

I just looked at what I got again. I got PS AS4 for fronts and PS 4 for the rears. I must have overlooked 4 for all seasons. Lol. My stock P Zero RF is also Summer tires. So I guess I'm OK.

Why are you running different tires? That’s a bit dangerous.

[10101X5]

Originally Posted by AGONXF30

Why are you running different tires? That’s a bit dangerous.

What makes you think it’s dangerous? It drives fine, rain or shine. I just wanted to get risk of the rf and didn’t want to go with these tires in question. I did overlook and thought they were the same. Imo, as long as you have same for each pair, you should be fine. I helped run a used tires shop in my early years. People had one tire changed all the times. As long as they are the same size, new or good used, they didn’t care. People seemed to be fine. Ideally all tires should be from same product line but I really don’t know how much of a difference one can feel. Any tire expert here?

[mnx5er]

Originally Posted by 10101X5

What makes you think it’s dangerous? It drives fine, rain or shine. I just wanted to get risk of the rf and didn’t want to go with these tires in question. I did overlook and thought they were the same. Imo, as long as you have same for each pair, you should be fine. I helped run a used tires shop in my early years. People had one tire changed all the times. As long as they are the same size, new or good used, they didn’t care. People seemed to be fine. Ideally all tires should be from same product line but I really don’t know how much of a difference one can feel. Any tire expert here?

This is such an interesting topic. Back in the old days of rear wheel drive only vehicles I knew many people who had different tires on each axle. Obviously how fast tires wear is a concern, but even BMW traditionally has not been a fan of rotating tires.

Reselling a car with mixed tires is not as easy, but I can sure see scenarios where the front and rear tires are different. BMW starts with staggered tires which already gives the two axles different traction and driving characteristics.

I think this is another creative way to deal with the 21" staggered setup not having a good AS option.

[swainbmw]

Originally Posted by elbandito

I appreciate the suggestion. I’m considering it and 50/50. What’s pulling me away from doing what you’re saying is I guess the inconvenience of needing to switch them out seasonally

NY winters + commute can get bad and so I’m trying to find what could be a good balance

If you’re in New York, definitely a dedicated winter set up is the only way to go .

[Av8or10]

Originally Posted by walkday

If you have decided on all-season tires, the best option is to go up one size. I put on Michelin Primacy Tour A/S 315/40 rear and 275/45 front on my 741m staggered rims. No rubbing even on the lowest air suspension setting. They are not run-flats, so I also added a good tire kit in the trunk for minor repairs. The 45e doesn't have space for a spare tire.

I'm considering purchasing the exact tires in this size. Did you receive any guidance from BMW if this tire size would work long term? What settings or adjustments did you make in the drive system? This tire setup is roughly 1"(3.5%) taller than the stock tires. My concern is how this will affect the drivetrain long term and if there were to be an issue, would BMW cover it under warranty?

I'm eager to hear your thoughts and experience with this setup.

-Mike

[10101X5]

Originally Posted by walkday

If you have decided on all-season tires, the best option is to go up one size. I put on Michelin Primacy Tour A/S 315/40 rear and 275/45 front on my 741m staggered rims. No rubbing even on the lowest air suspension setting. They are not run-flats, so I also added a good tire kit in the trunk for minor repairs. The 45e doesn't have space for a spare tire.

This would be nice because the GLE has these and drives very nice. But doesn't it mess up the odometer?

[Av8or10]

Originally Posted by 10101X5

This would be nice because the GLE has these and drives very nice. But doesn't it mess up the odometer?

That's what I was thinking, too. My wife has a GLE with those exact tires and sizes and we have been happy with them.

[915M]

Originally Posted by 10101X5

This would be nice because the GLE has these and drives very nice. But doesn't it mess up the odometer?

IT will read slightly higher than what actually it is unless BMW use GPS speed on speedometer.
Also, you will have 3000 less miles per 100k miles of drive on odometer

[Photographer918]

I went with a square 20 inch set up, using the same 275/45 R20 size that are my primary tires. My dealership got me options and I’ve been really happy with the Michelin Alpin 5 snow tires I bought….

[jad03060]

You really want your tires to all be within 2% or you will be putting extra wear on the differentials.

The vehicle (well, all vehicles) are designed to have the same tread on each corner. You probably wouldn't run into an issue unless you were in a bad situation where balance, stopping distance, and cornering grip were reaching the maximum. FWIW, the same tire, one with the BMW star on the sidewall, and one without the star can have different rubber, tread pattern, cord structure...BMW and the tire manufacturer spend a fair amount of time tuning the tires to the vehicle. You may not notice except maybe back-to-back drives, but there will likely be NVH differences, potentially different grip or longevity between what may look like identical tires. That's not to say that a tire in the proper size won't work on the vehicle, but it may not be BMW's idea of optimal.