[Mr. Hankey]

Been working on what size tires I will run on my M2, then will find rims to fit. I am a big fan of Michelin PS4S so here are the specs for those from 275-305 for 19" and 20" rims. I didn't include the 18's because I won't be tracking this car much and don't want scored hubs or calipers from rocks which happened on my F80 running 18s.



Note: The 19" 305 doesn't come in a 35 height and has smaller diameter than stock. Calculated width is just the section width (275) converted to inches. The book width is what Michelin quotes when mounted on the "ideal rim" in the column to the right. So the 275 on the "Ideal" 9.5 inch rim will have that book width of 10.9 inches. Obviously if you pinch or stretch the tires on larger or smaller rims those numbers will change (about 0.2" for every 0.5" change in rim width if I remember correctly). I also don't think the "Ideal rim" they are quoting here really means the ideal size for maximum tire performance, it's just for sizing.

I've always thought these cars should maintain the stagger for efficiency up front and more of an oversteer-y setup, but I'm really intrigued by a square setup, maybe a 19", 10.5 around with 285s. They will be well supported in that size.

I cannot find effective "tread widths" anywhere for these tires. Michelin used to publish them and that's important because the PSS 295s had more effective tread/contact patch than the 305s in 19" due to wider/extra groove in the 305 for hydroplaning resistance...if anyone knows this data for the PS4S I'd greatly appreciate it!

[Mr. Hankey]

The insanity continues. This is a chart showing how much wider the tires are than the corresponding rim width. Too far out of bounds and there will be handling consequences (squishiness and dampening/"Comfort" vs. sharper/"Sporty" feel and faster loss of grip at limits). The % wider than the ideal rim width are just based on Michelin's own published tire width vs the "ideal rim" that will give you that published width. For me I like a sharper feel so will gravitate towards the 8-10% range...again making me think the 285 square setup on 10.5" rims might work really well.

[MineralGreyMetallic]

I'm not sure if this helps your dataset, but this is the setup I'm going with

Front
10.5x20 ET14 for 285/30 R20

Rear
11x21 ET12 for 305/25 R21

You seem to know a lot about the change in dynamics at these various sizes. I started a thread asking what the consequences of this setup would be for handling but didn't get much traction.

This setup seems to be within your "green range" for both tires, although you haven't specifically listed 11x21 305.

Any thoughts?

[Ronin76]

Ah sh!t, this may be a thread I have to pay attention to but wheel and tire sizes confuse me.

[Mr. Hankey]

Originally Posted by MineralGreyMetallic

I'm not sure if this helps your dataset, but this is the setup I'm going with

Front
10.5x20 ET14 for 285/30 R20

Rear
11x21 ET12 for 305/25 R21

You seem to know a lot about the change in dynamics at these various sizes. I started a thread asking what the consequences of this setup would be for handling but didn't get much traction.

This setup seems to be within your "green range" for both tires, although you haven't specifically listed 11x21 305.

Any thoughts?

I think both those sizes are great! 285 on a 10.5 and a 305 on an 11 are well supported and those are the 2 sizes I’m looking at myself. Meaning the sidewall isn’t too far away from the edges of the rim.

I didn’t know that a 21” rim was an option! Living in New England we have a lot of frost heaves and potholes so didn’t even look. Here that tire would get blown off the rim or worse a bent rim. I couldn’t be driving around on eggshells, that’s why I was considering 19s all around.

With the 21 your ride will be a little firmer, response a little better due to the shorter sidewall…although whether you will feel that through the steering is another question.

I wonder why BMW staggers 19” front and 20” rear? Maybe for comfort in the front, and the rear for a little less tire flex on acceleration? I’m thinking they are maximizing performance out back, however small, and adding comfort in the front and some flex to the tire with the higher sidewall, again however small…

I’m tempted to keep 19/20 to use the stock tires, but think I might just go 20 around.

[Mr. Hankey]

Originally Posted by Ronin76

Ah sh!t, this may be a thread I have to pay attention to but wheel and tire sizes confuse me.

Me too. Hence the spreadsheets. I'm sure the folks who just know this stuff will look at it and laugh (and I'd appreciate their input in that case), but everything is a tradeoff. It may be to fit the "ideal" wheel/tire combo will require an offset that puts them out of the wheel wells and chips the side of the car up, or if its in too much rubs the liner...

For me I don't want to chew up the sides of the car, but I also don't want to have to worry about accidentally hitting the errant pothole here and there...oh and will go to the track a couple times a year.

[Ronin76]

OK, here goes what I have been thinking about (I do not have my car yet). I live in Pittsburgh, PA so need something for winters as well. Fortunately we have not had a lot of snow the last few years but I also did not plan on driving in the snow, just need good winter tires that would serve me well in cold weather. That also played in a role in my decision making. I am sure my choices are flawed...

Spring/Summer Set Up: Michelin Pilot Sport 4S

Front: 19” x 10 ET 11mm with 285/30-19*
Rear: 20” x 11 ET 8mm with 305/30-20

*I went with 30 instead of 35 because I thought I read some people who went with 35 would rub in the front?? With all these numbers I may have misread.

Winter Option 1: Michelin Pilot Alpin PA4

Front: 19” x 10 ET 11mm with 285/30-19*
Rears: 20” x 11 ET 8mm with 305/30-20

*these were the reason I also went with 30 for the front summer. I thought if it worked with the winter it would work for the summer.

Winter Option 2: Continental Conti Winter Contact TS830 P

Front: 19” x 9.5 ET 5mm with 265/40-19
Rear: 19” x 10.5 ET 5mm with 295/40-19

Not sure if the 40mm height would be an issue

[Mr. Hankey]

Originally Posted by Ronin76

OK, here goes what I have been thinking about (I do not have my car yet). I live in Pittsburgh, PA so need something for winters as well. Fortunately we have not had a lot of snow but I did not plan on driving in the snow just need good winter tires that would serve me will in cold weather. That so played in a role in my decision making. I am sure my choices are flawed...

Spring/Summer Set Up: Michelin Pilot Sport 4S

Front: 19” x 10 ET 11mm with 285/30-19*
Rear: 20” x 11 ET 8mm with 305/30-20

*I went with 30 width instead of 35 because I thought I read some people who went with 35 would rub in the front?? With all these numbers I may have misread.

Winter Option 1: Michelin Pilot Alpin PA4

Front: 19” x 10 ET 11mm with 285/30-19*
Rears: 20” x 11 ET 8mm with 305/30-20

*these were the reason I also went with 30 for the front summer. I thought if it worked with the winter it would work for the summer.

Winter Option 2: Continental Conti Winter Contact TS830 P

Front: 19” x 9.5 ET 5mm with 265/40-19
Rear: 19” x 10.5 ET 5mm with 295/40-19

Not sure if the 40mm height would be an issue

Spring/Summer Set Up: Michelin Pilot Sport 4S
Front: 19” x 10 ET 11mm with 285/30-19*
Rear: 20” x 11 ET 8mm with 305/30-20

Are you lowering your car? If not then I suspect the 285/35-19 will work. My impression is that the 35 *might* rub the wheel well liner at full lock. If lowered then potentially higher chance of that rub happening. I believe a 5 mm spacer would fix that if it happened.

Winter wheels - Why not just use the stock rims for winter and run a 275/19 up front and a 275/20 out back? I believe Nokian makes Hakkapellita R3s in those sizes. Fabulous winter tire. If only driving the car in winter on nice days (ie not in actual snow) then Michelin pilot sport AS tires would work well on the stock rims.

I live in new england and the stock rims will have my winter tires mounted. I will go with the Nokians. OK to run the square tire setup in the winter, the 275s will stretch, I ran them on my 9.5/10.5" M3 rims no problems for 7 years.

[Ronin76]

Originally Posted by Mr. Hankey

Spring/Summer Set Up: Michelin Pilot Sport 4S
Front: 19” x 10 ET 11mm with 285/30-19*
Rear: 20” x 11 ET 8mm with 305/30-20

Are you lowering your car? If not then I suspect the 285/35-19 will work. My impression is that the 35 *might* rub the wheel well liner at full lock. If lowered then potentially higher chance of that rub happening. I believe a 5 mm spacer would fix that if it happened.

Winter wheels - Why not just use the stock rims for winter and run a 275/19 up front and a 275/20 out back? I believe Nokian makes Hakkapellita R3s in those sizes. Fabulous winter tire. If only driving the car in winter on nice days (ie not in actual snow) then Michelin pilot sport AS tires would work well on the stock rims.

I live in new england and the stock rims will have my winter tires mounted. I will go with the Nokians. OK to run the square tire setup in the winter, the 275s will stretch, I ran them on my 9.5/10.5" M3 rims no problems for 7 years.

Hi,

Yes I plan on getting the MP HAS kit lowered 10mm. I think that is as low as I am willing to go. Regarding the summer, I came up with this setup based on rcouchh. Only difference is that I believe he is even lower than the 10mm. Currently he is using the OEM tires so there is a bit of a stretch to them but he plans on going with 285/305. According to him, he is not experiencing any rubbing.

For the winters, thanks for the info. I was not sure if it was OK to have an OEM size up front (275) and then have a stretched size (275 instead of a 285) in the rears. The only thing about using the OEM wheels is that I would probably have to get spacers which is something I would trying to avoid. That being said, it would save me a few grand on getting another set of wheels. Also if using the winters for only 4 months maybe having spacers is not that big of a deal? What side wall specs would you recommend 35s for front and rears? 35 fronts and 30 rears?

[Mr. Hankey]

Originally Posted by Ronin76

Hi,

Yes I plan on getting the MP HAS kit lowered 10mm. I think that is as low as I am willing to go. Regarding the summer, I came up with this setup based on rcouchh. Only difference is that I believe he is even lower than the 10mm. Currently he is using the OEM tires so there is a bit of a stretch to them but he plans on going with 285/305. According to him, he is not experiencing any rubbing.

For the winters, thanks for the info. I was not sure if it was OK to have an OEM size up front (275) and then have a stretched size (275 instead of a 285) in the rears. The only thing about using the OEM wheels is that I would probably have to get spacers which is something I would trying to avoid. That being said, it would save me a few grand on getting another set of wheels. Also if using the winters for only 4 months maybe having spacers is not that big of a deal? What side wall specs would you recommend 35s for front and rears? 35 fronts and 30 rears?

Yes rcouchh's car is pretty slick, I saw that as well (that car reminds me of a bad ass STi from the back, M2-baru if you will, not a diss I love it). I prefer to keep the 35 sidewall height on the 19s but I also know a lot of folks go to the 30 height when widening and when lowered, presumably to avoid rubbing? Doubtful to give the car negligible rake or concern of messing with traction control if inverting the diameters to shorter out back than in front. Maybe for a bit of a sharper feel up front, obviously using up the stock rubber which is smart.

Regarding using the stock rims in the winter with winter tires. And this is just me. But I would not run spacers with my winter tire setup. They won't rub. I want those tires squarely within the wheel well. Lots of little cinders/sand/salt from road treatments that could get kicked up the side of the car in winter so I'm happy to have them tucked in to minimize that. Also with spacers in winter there can be some corrosion issues with the spacer and the hub and the wheel when mixed with salt and water, just not clean. If you're worried about stretching the 275s on the 10.5 in the rear see if you can pick up a couple 9.5s on here in the classifieds - cheaper than an entire dedicated set of rims - bam, instant square winter setup. I would rotate my winter tires front to back every 2 years with the 9.5s up front and the 10.5s out back.

Not sure how Pittsburgh is in winter but I'm sure you get snow/ice and roads are dirty from time to time. Gorgeous area, love Pittsburgh and the surrounding rolling hills in PA, gorgeous. And I'm sure a lot of good roads!

[Ronin76]

Originally Posted by Mr. Hankey

Yes rcouchh's car is pretty slick, I saw that as well (that car reminds me of a bad ass STi from the back, M2-baru if you will, not a diss I love it). I prefer to keep the 35 sidewall height on the 19s but I also know a lot of folks go to the 30 height when widening and when lowered, presumably to avoid rubbing? Doubtful to give the car negligible rake or concern of messing with traction control if inverting the diameters to shorter out back than in front. Maybe for a bit of a sharper feel up front, obviously using up the stock rubber which is smart.

Regarding using the stock rims in the winter with winter tires. And this is just me. But I would not run spacers with my winter tire setup. They won't rub. I want those tires squarely within the wheel well. Lots of little cinders/sand/salt from road treatments that could get kicked up the side of the car in winter so I'm happy to have them tucked in to minimize that. Also with spacers in winter there can be some corrosion issues with the spacer and the hub and the wheel when mixed with salt and water, just not clean. If you're worried about stretching the 275s on the 10.5 in the rear see if you can pick up a couple 9.5s on here in the classifieds - cheaper than an entire dedicated set of rims - bam, instant square winter setup. I would rotate my winter tires front to back every 2 years with the 9.5s up front and the 10.5s out back.

Not sure how Pittsburgh is in winter but I'm sure you get snow/ice and roads are dirty from time to time. Gorgeous area, love Pittsburgh and the surrounding rolling hills in PA, gorgeous. And I'm sure a lot of good roads!

Hi, thanks again for all the useful info...told you I suck at wheels and tires.

Our winters have not been bad the last few years as far as snow goes but it does get pretty cold at times. If it does snow we would just use the wife's SUV. Luckily we work for the same company so it would work out.

I hear you regarding not using spacers for the winter setup. It will look a little silly but it probably would be for the best. I did not think about possibly corrosion, that is a good point.

I think if using the OEM wheels for winter then I will use 275/35-19 up front and 275/30-20 in the rear. Just to keep it as close to OEM as possible.

Thanks again!!