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Good day,
In order to run a lower profile, I'm thinking about switching from 19" to 18" wheels.
I am thinking about changing from 255 35 19 et39 and 225 35 19 et37 to 255 40 18 and 235 40 18 mounted on 8.5 and 9.5 x18s et38 and 42, accordingly.
Is this staggered arrangement used by anyone? Is everything alright?
Really gratefully.
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Dimensions of tires and wheels
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LiamTheGreat
- Posts: 79
- Joined: Mon Feb 02, 2026 8:35 pm
I do not know much about the sizes 255 and 225, but I remember seeing a 35 and a 40 on the fuel filler flap, so that could give you a clue.
I think others will soon follow with more reliable information.
I think others will soon follow with more reliable information.
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NirviusTom
- Posts: 59
- Joined: Mon Feb 02, 2026 8:59 pm
The roads near here are like farm tracks, so I want to improve the ride quality by going up in profile. Yet, I believe 255/35 and 225/40 are factory fits with 18s.
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andy_bmw_1965
- Posts: 60
- Joined: Mon Feb 02, 2026 8:37 pm
In the long run, what do you hope to accomplish?
The values of 19–18 can be useful for rim protection with RFT. It is arguable as they are M sport specs.
Investing your effort and money on run RFT noise and ride enhancement is a waste.
You are getting a 15 mm flexing side wall, so if it's noise and riding on a non-run flat, you will see benefits.
Going with 17" on regular tires, even with the sport suspension, will greatly improve the ride and noise levels.
My wife, who is often seeing things when I don't, came in and asked, "What have you done to the car?" after I did the exact same thing on my m sport.
Changing from 19" tyres with 30 and 35 walled to 45 standard tyres on 17" with a 28mm sidewall gave the car the performance you'd expect from a high-quality vehicle. The old 19s were a noisy, painful, and bumpy ride. Now it's peaceful, easy on the road, and responsive. I never imagined it was possible to reach 100 km/h, but now I can hear faint rubbing against the upholstery. I haven't backed it into a corner just yet, but I'm hoping it will be alright because the new tires are high-performance summer tires.
The sweet spot, in terms of appearance and number of those who fell, is 18. The roads around here don't seem out of place with the 17s, so I wasn't sure it would be my fix. So BMW was pleased with the marketability of "the look" since the car had 17 to 19" wheels.
This involves the acquisition of a space saver and a jack, though. Remember that an RFT is worth more than twice the amount as a regular car tire, and you're out of luck if you drive on a flat tire. I think they're a terrible product for the customer, but I bet they saved BMW a tonne of cash. If needed, we can also find a regular tyre outside of the city limits compared to an RFT within the same day. Plus, I can easily inflate a standard tire at home; all my family's needs is to bring it alongside them on vacation, and that's exactly the point of a space saver.
I stopped at 235/45/17.
The values of 19–18 can be useful for rim protection with RFT. It is arguable as they are M sport specs.
Investing your effort and money on run RFT noise and ride enhancement is a waste.
You are getting a 15 mm flexing side wall, so if it's noise and riding on a non-run flat, you will see benefits.
Going with 17" on regular tires, even with the sport suspension, will greatly improve the ride and noise levels.
My wife, who is often seeing things when I don't, came in and asked, "What have you done to the car?" after I did the exact same thing on my m sport.
Changing from 19" tyres with 30 and 35 walled to 45 standard tyres on 17" with a 28mm sidewall gave the car the performance you'd expect from a high-quality vehicle. The old 19s were a noisy, painful, and bumpy ride. Now it's peaceful, easy on the road, and responsive. I never imagined it was possible to reach 100 km/h, but now I can hear faint rubbing against the upholstery. I haven't backed it into a corner just yet, but I'm hoping it will be alright because the new tires are high-performance summer tires.
The sweet spot, in terms of appearance and number of those who fell, is 18. The roads around here don't seem out of place with the 17s, so I wasn't sure it would be my fix. So BMW was pleased with the marketability of "the look" since the car had 17 to 19" wheels.
This involves the acquisition of a space saver and a jack, though. Remember that an RFT is worth more than twice the amount as a regular car tire, and you're out of luck if you drive on a flat tire. I think they're a terrible product for the customer, but I bet they saved BMW a tonne of cash. If needed, we can also find a regular tyre outside of the city limits compared to an RFT within the same day. Plus, I can easily inflate a standard tire at home; all my family's needs is to bring it alongside them on vacation, and that's exactly the point of a space saver.
I stopped at 235/45/17.
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LiamTheGreat
- Posts: 79
- Joined: Mon Feb 02, 2026 8:35 pm
I suppose any size could be used as long as the diameter on the outside was consistent to avoid breaking the ABS.
There has to be a calculator ready online for that.
There has to be a calculator ready online for that.
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ALJohns_34
- Posts: 31
- Joined: Mon Feb 02, 2026 8:39 pm
I am using factory-installed 225/40/18 down on the front and 255/40/18 on the back, with a 35 profile. All is working fine. Someone previously you cracked the back MV3 and boosted the profile. That's the way I like it. I'm not entirely sure if I know–these roads would be better on 17s or 16s.
