Choosing the appropriate tyres for the BMW 3 Series F30. Front and Rear

[Matt865]

Greetings, everyone.

I have had my BMW for a duration of 4 years, during which I consistently choose for the direct replacement of the tyres. Can someone provide guidance on whether the tyres are appropriate and, if so, explain the reason for the discrepancy between the rear and front tyres?

The tyres are Bridgestone Potenza Run Flats with a size of 225/45 R18 and a load index of 91.
The rear tyres are Bridgestone Potenza Run Flats with a size of 255/40 R18 and a load index of 95.

I appreciate your assistance beforehand.

[Paulinelinker]

A staggered configuration, where bigger tyres are often used on the rear, is a prevalent practice.

In order to verify the accuracy of the tyre sizes, please provide us with the specific model of your BMW. However, anticipate receiving several suggestions to discard the runflat tyres. Personally, I strongly support them.

[Matt865]

Thank you for responding. Paulinelinker, it is reassuring to learn that a staggered configuration is considered common.
The vehicle in question is a BMW 3 Series, namely the 2.0 320d MSport Auto Euro 6 (s/s) 4-door model from the 66 Plate.
Is that assistance satisfactory?

[Alex1978]

The vehicle in question is an F30 model, which is most likely equipped with Style 400 alloy wheels.

Specifications shown below:

https://www.carsaddiction.com/en/wheels/bmw/style-400

[Matt865]

I apologise, that is really F30. Those are definitely my wheels. Not my literal wheels, but you get the intended meaning.
Based on your post, it seems that you have also chosen the appropriate tyres.
Thank you very much. Therefore, my only remaining question is if it is significant if the speed rating differs.
For my current tyres with a load index of 91, may I replace them with 225/45 R18 Y95 tyres instead of 225/45 R18 Y91 tyres?
Is there a discernible impact?

[Alex1978]

The load rating is indicated by the numbers "91" and "95".
The speed rating is denoted by the letter "Y".
As long as you meet or above the manufacturer's officially approved rating, it doesn't matter whether the front and back are different.

The user's text consists of a single emoticon, specifically a smiley face.

Additionally, I recommend removing the run-flat tyres.

[VWDaveBMW]

I agree with getting rid of the run-flat tyres.
It will modify the automobile.

[Paulinelinker]

Unless you get a tyre rupture on a 'smart' motorway that has a designated emergency lane.

[Matt865]

Does it have any significance if the load rating shifts from 91 to 95?
The back is already at 95.

I am considering purchasing either the Hankook Ventus S1 Evo 3 HRS 225/45 R18 Y 95 or the Michelin Pilot Sport 4 ZP 225/45 R18 95.

To replace the Bridgestone Potentza 225/45 R18 Y 91

Opinions?