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Non-Runflat Tire Pressure for the BMW E91


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I now own a BMW 320d E91 model with an engine power of 184 horsepower. The vehicle is equipped with Runflat tires, but I am interested in replacing them with non Runflat tires. Specifically, I am seeking to install four tires with dimensions of 225/45/17.
The inquiry pertains to the various pressures exerted on the sticker, specifically in relation to RFT (Run-Flat Tire) models.
Does anybody have knowledge of a method or a reliable online resource where I may get the appropriate tire pressure for this specific circumstance?

It is important to note that rotary flexible tubes (RFTs) need a greater pressure.

I appreciate your assistance.

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Thank you for your input. I will proceed with implementing the suggested changes.

I have come across several instances when individuals have spoken with tire manufacturers or BMW through email, and the response has always emphasized adhering to the information provided on the sticker. However, it remains uncertain if this response really reflects the factual answer or is just a politically correct statement.

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I recently replaced the wheels and tires on my vehicle with a size that deviated from the specifications shown on the door label. To ensure accuracy and compatibility, I used a tool for this purpose. The purpose of this tool is to calculate the optimal pressure for vehicle tires.

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Yesterday, I spoke with BMW Portugal through email, whereby I provided a detailed account of the circumstances surrounding the change of tires and their respective pressure.
The response was placed underneath the acronym "NEET."

Dear Dave, I hope this message finds you well.

We therefore confirm the receipt of your correspondence, which has merited our careful consideration.

In light of the aforementioned, and in consideration of your inquiry, we would like to apprise you that the tire inflation pressures, which are suitable for the tire dimensions sanctioned by the manufacturer, may be found in column B of your BMW. In this scenario, the inflation pressure pertaining to the tire size in question is applicable, irrespective of the presence or absence of RunFlat technology. Tire pressure requirements pertain to tires under ambient temperature conditions, which also extends to the cold inflation pressure.

During extended journeys at elevated speeds, the tires experience increased heat generation as a result of friction with the road surface and the interaction between the tire tread and the ground. Consequently, this leads to a rise in tire temperature, which subsequently causes an elevation in tire pressure.

Thermal expansion occurs when there is a significant disparity between the surrounding temperature and the air temperature inside the tires, resulting in increased inflation pressure.

Furthermore, in order to achieve this objective, it is important to consider the fundamental physical rules governing pressure and temperature. In this context, the following rule is applicable: An elevation in temperature by 10°C leads to a corresponding rise in the inflation pressure of the tires by about 0.1 bar.

In this manner, and for the purpose of elucidation, we now provide the following illustration, pertaining to the domains of temperature and pressure.

When conducting the inflation process of a tire using hot inflation pressure, the temperature of the tire inflation was recorded to be 70°C.
Consequently, the adjusted tire inflation pressure has been revised to 2.4 bar. Following an extended period of immobilization, the tire undergoes a cooling process until it reaches the ambient temperature of 20 °C. This temperature decrease equates to a temperature differential of 50 °C in respect to the initial tire inflating pressure. Consequently, the tire inflation pressure decreases to a new value of 1.9 bar, which is obtained by subtracting 0.5 bar from the initial pressure of 2.4 bar.

We trust that we have received comprehensive elucidations about the aforementioned matter, and that we have adequately addressed the inquiries you have posed.

We express our gratitude for your choice to prioritize our brand and goods, and extend our sincerest respects to you.

The BMW Group, a multinational automotive company, has a presence in Portugal.
Bruno Monteiro is employed in the field of customer service.

The office address is Lagoas Park, Ed. 11 – 2nd Floor, 2740-270 Porto Salvo, Portugal.

In this particular scenario, it might be argued that the principle of KISS (keep it simple stupid) is applicable.

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