Pics of 245 and 275 tires on stock OEM 18s

[Arith2]

Ya think?! Glad I'm not your kidneys.

I have to toughen them up so I don't end up on dialysis. Plus the door says 41 and 48 psi for speeds that exceed 100mph. A lot of 911s are in the 40s for tire pressure. Sometimes those cars call for 50psi for full load.

[scotty737]

I have to toughen them up so I don't end up on dialysis. Plus the door says 41 and 48 psi for speeds that exceed 100mph. A lot of 911s are in the 40s for tire pressure. Sometimes those cars call for 50psi for full load.

What’s the benefit of this? Are you moving around 1000lbs of people lol

[repoman89]

48 psi? Imagine how small that contact patch must be lol.

[Arith2]

48 psi? Imagine how small that contact patch must be lol.

The tires are wearing perfectly. I don't want a larger contact patch with the downforce created at higher speed. It's basic aero and tire knowledge. BMW did the research that is what their data showed them. I'll follow that research until someone proves it wrong. I have a CSL trunk which will significantly increase that downforce. I'm not trying to melt my tires.

[repoman89]

Your CSL bootlid is not even close to creating the five hundred pounds of downforce that would justify following the max load pressure recommendation, and BMW research would have been on ancient PS2 tires. I haven't melted any tires yet running mid to high 30psi hot on fast tracks.

[T.J.]

The tires are wearing perfectly. I don't want a larger contact patch with the downforce created at higher speed. It's basic aero and tire knowledge. BMW did the research that is what their data showed them. I'll follow that research until someone proves it wrong. I have a CSL trunk which will significantly increase that downforce. I'm not trying to melt my tires.

follow BMW correctly, not the max load pressures

[Tbonem3]

Me running 30psi on pss 😒

[Sharocks]

Your CSL bootlid is not even close to creating the five hundred pounds of downforce that would justify following the max load pressure recommendation, and BMW research would have been on ancient PS2 tires. I haven't melted any tires yet running mid to high 30psi hot on fast tracks.

Yooo facts lmaoooo

[Casa de Mesa]

I'm gonna piss some people off. I run 29F/27R cold with just me in the car. I set based on temps and load inflation tables. As soon as you move away from stock sizes, the BMW recommended pressure go out the window.

Re: the CSL trunk, it at best adds marginal downforce. Sure some, but not serious DF. I don't have the data, admittedly, but it's a bootlid kicker basically. No way that constitutes a lot of downforce like a proper inverted airplane wing does.

[Sharocks]

M3 E46
Wind channel
Lift Force at 200 Km/h (160mph) : 18kg (39.6lb) at rear axis
cW Value: 0,32

M3 CSL
Wind channel
Lift Force at 200Km/h (160mph) : -10kg (-22lb) at rear axis
cW Value: 0,33

So the CSL produces 61.6lb more downforce at 160mph than the standard M3.
Note that this is the complete car, but since it's measured at the rear axis, you can estimate that the majority of this is produced by the trunk lid.

Stole this from the Googles.

[lvm3sm46]

Tire melting for sure that 60lb of downforce at 160mph.

[lastMleft]

I have style 67s with 245/275. Bad picture but here.

Nice stock set up! Any rubbing up front?

[scotty737]

Nice stock set up! Any rubbing up front?

I think it rubs at full lock on the fender liner but I don’t remember. Haven’t had them on in a couple years. Nothing bad if any.

[Arith2]

I go over 100 a lot and most of my driving is above 70mph. Post what you want but these are the pressures I run because they suit my driving situation. My tires look great, handle great, and hook up quite well. It works and I'm going to keep doing it. A chart isn't going to change that.

[Casa de Mesa]

I go over 100 a lot and most of my driving is above 70mph. Post what you want but these are the pressures I run because they suit my driving situation. My tires look great, handle great, and hook up quite well. It works and I'm going to keep doing it. A chart isn't going to change that.

Never seen those stickers on a BMW before. Are those original to the car? I'm genuinely curious.

Regardless, if you aren't running stock tire sizes with the same load rating, those stickers are a suggestion. If you use a true pyrometer with a probe (not an infrared thermometer), I'd be curious what yours temps are across the face. I can almost guarantee your centers are hotter than the sides at normal highway speeds (70mph). How often are you above 100mph for an extended period of time?