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[mrh335]

I searched and can't find the answer other than a non-openable excel spreadsheet.

I have a 2011 E90 M3 and have the staggered Sport A7 Wheels with the Dunlop Sport 3D tires. This is the 235/40 R18 and 255/40 R18 setup.

I would like to know what the best tire pressure would be for this wheel tire combination. I made the mistable on my 2007 E90 to use the recommended pressure for 17" M&S with my 17" Blizzaks and in the end my rear tires wore out down the center of the tire signifcantly more than the inside or outside edges make overall traction crappy. Therefore, I do not plan to follow the recommendations for 18" tires in the BMW literature.

At present, I have them inflated to 34 psi rear and 32 psi front. I took measurements of each tire with a digital tread depth gauge at the outer, center, and inner treads for each tire and was going to monitor, but if someone else already did the homework to find the proper pressure for correct tire wear and good traction, please post it up.

[linuxd00d]

Reviving an old thread as I am now asking the same question.

Running the same Dunlop Winter Sport 3Ds as the OP on the stock set of 219M wheels. Discount Tire inflated all four corners to 38psi. Wondering what pressure I should really go with.

[mrh335]

After driving on the tires for two winters I can tell you to underglaze several psi. My tears have prematurely worn on the center lines to the winter wear indicators, but the inner and outer tread is deep meaning I need to replace them early. The fronts have worn evenly running 1 or 2 psi under the sticker.

[linuxd00d]

What does "underglaze" mean?

[advans]

I think the tire pressure should be similar to stock 18s?

[mrh335]

Originally Posted by linuxd00d

What does "underglaze" mean?

That was supposed to be underinflate.

If you run at stock oem 18 inch pressures, then the tire center will wear much faster

[linuxd00d]

Originally Posted by mrh335

If you run at stock oem 18 inch pressures, then the tire center will wear much faster

Thanks. Are you recommending 33 on all four corners?

[mrh335]

Originally Posted by linuxd00d

Thanks. Are you recommending 33 on all four corners?

If I were to replace my tires, I would run the rear 33 or 34 and run the front at 34 or so. Like I said before, the fronts are about 1 or 2 psi less than the pressure on the door jam.

I am not sure how this will affect handling and top speed capabilities. The tires require a certain amount of pressure to support the car as down force increases with speed. They also need to provide side support while turning and enough pressure not to damage the wheel with a pothole.

If you live in a warmer area or have a warm winter like I did last year, then the risk is the tires are soft and easy to over pressurize.

It would be nice to have a tire expert provide help on this to ensure we are inflating our tires to a dangerous level.

With that said, I have no recommendation to what you inflate tires to especially if it is different than what is written on the door jam. I am just sharing what I might do and have done.

[linuxd00d]

Originally Posted by mrh335

With that said, I have no recommendation to what you inflate tires to especially if it is different than what is written on the door jam. I am just sharing what I might do and have done.

Are you an attorney? Don't worry, I'm not going to sue you if my tire explodes. This is an internet forum. I take advice as what it is: advice from the internet

Thanks for the feedback. I think I'm going to try 33F / 35 or 36R since that's what the book recommends for 18" M+S tires. And I may lower the rear if I notice the uneven wear you describe.

[mdosu]

how does the 255/40/18 fit on stock 18s? I use to use 245/40/18 all around, and sometimes the seal leaks in the rear wheels. The last 2 years, it would leak about 5 psi every 2 weeks. I went with 265 40 18s this year in the rear

[linuxd00d]

Originally Posted by mdosu

how does the 255/40/18 fit on stock 18s? I use to use 245/40/18 all around, and sometimes the seal leaks in the rear wheels. The last 2 years, it would leak about 5 psi every 2 weeks. I went with 265 40 18s this year in the rear

I got mine mounted 2 days ago, so I can't comment long term. I think I can tell visually that the tires are a little less wide than the stock 265, but that could be because I know they are. I doubt they will leak, I spent a ton of time researching this topic and 235F/255R is a very common winter size for our wheels.

What winter tire did you get in 265/40/18? I didn't find any good option in that size.

[WarrantyTracker]

I'm using the 255s in the rear with no problem thus far.