Pics of 245 and 275 tires on stock OEM 18s

[Casa de Mesa]

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.

This is actually more than i thought it would be. But still, only a few sacks of potatoes.

[T.J.]

The sticker in the door jam is for worst case loading scenario, not best performance
More reasonable speed adjustments are here: https://m.tirerack.com/tires/tiretec...jsp?techid=302
But you’re not cruising at 150 right

[repoman89]

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.

Good find and more than I thought it’d be as well, but for sure not enough to bother changing tire pressures — barely puts the car into downforce rather than takeoff mode. Though 200kph is actually 125mph not 160.

The CSL front bumper is supposed to slightly reduce lift as well (I’ve seen 11 pounds but with no speed attributed to it so could be bs), probably mostly from the air dams/lips.

[05Mdriver]

Appreciate the replies guys, and since we are staying on topic, what did everyone have for dinner tonight ?

[stephen]

Jerk chicken. But I had to inflate it to 48psi to toughen it up and ensure the heat was distributed evenly.

[cobra]

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

It actually looks fine, nice

[Casa de Mesa]

Appreciate the replies guys, and since we are staying on topic, what did everyone have for dinner tonight ?

Fair point. Point taken. Pressure cooked pork chops.

But this is the internet. And the tangents have been at least been loosely related. I can't help you with your original question tho.

[t44tq]

People have been doing this for a long time in Stock (now Street) class autox. Really depends on the tire and the results of testing. Considering that it's not out of spec for the tire, what's the problem?

[maw1124]

Considering that it's not out of spec for the tire, what's the problem?

Looks apparently... judging from what OP asked... so far it seems we have "bulgy, but it works".

maw

[05Mdriver]

The reason for the thread was that OEM size Michelin P4S are on back order till march while 245 and 275 are currently available, so was curious to see how they looked.

[maw1124]

235/265 might be the hit anyway... plus you don't want shit to be unavailable if you ever hit a nail the wrong way... learned that one the hard way one time too many... car down for a week waiting on an odd tire size where I stretched... GL

maw

EDIT... disregard 235/265... I keep forgetting we're talking 18" here.

[K-Dawg]

Really depends on the tire and the results of testing. Considering that it's not out of spec for the tire, what's the problem?

For a given size of a specific tire, the manufacturer provides an "acceptable" width range. Somewhere in that range, there's an "optimal" rim width. From a performance perspective, that width is probably on the wide end of the range.

The reason for the thread was that OEM size Michelin P4S are on back order till march while 245 and 275 are currently available, so was curious to see how they looked.

Personally, I'd still stick with original sizes. Super Sports appear to be available (but check the manufacture dates), otherwise I'd try Continental ExtremeContact Sports.

Also, there are 225/45/18 P4S on eBay, and TireRack says the 255/40/18 P4S should be available in a couple weeks.

[05Mdriver]

Wound up just ordering stock 225 and 255 super sports.. late 21 DOT codes which were important.

[Casa de Mesa]

Wound up just ordering stock 225 and 255 super sports.. late 21 DOT codes which were important.

Nice on the tires. Good decision.

Also going off the reservation here a tad... but nice garage.