Tread depth versus tire width for wet traction

dparm · 06-08-2020, 06:09 PM

This isn't directly about an M3, but I just ordered a second set of wheels and need to get some tires for street use plus wet track days. I don't have a massive selection of tires, so I am trying to understand some fundamentals of how to maximize wet traction.

All else being equal, what will provide better wet traction: a narrower tire or one with deeper tread?

In my case, I can get the OEM tire which has about 7.4/32" when new or get a tire slightly wider that has 9 or even 9.5/32". As I understand it, the car has a slightly shallower tread depth when new because it reduces tread squirm and provides better handling -- at the expense of wet traction.

aus · 06-09-2020, 01:07 PM

Narrower tire will dig deeper into standing water and have less hydroplaning.
Deeper tread will help evacuate the water, so you want both.
.

Redd · 06-09-2020, 07:00 PM

I think the narrower vs wider argument is moot due to the small range of tire width you have to play with. Going from 265mm down to 245mm isn't going to make a whole lot of difference in terms of cutting thru the water better.

You're better off focusing on tread depth (more the better) and most importantly tread design and compound. Tread design and tire compound is the main reason why tires like PS4S do so much better in the wet than other tires.

I think if you need a performance tire for street and wet track use, you're not gonna do much better than PS4S.

roastbeef · 06-09-2020, 07:31 PM

i'd say narrower would be better.

my m3 has 275/295's on it and it tends to dance around in the rain a little bit. it does have a fairly aggressive alignment, but i wear out the inside from camber wear before the tread is done, so they always have good tread.

my smart car has 155/60/15's and it handles heavy rain like a champ. cuts through standing water without issue. actaually drives really nice in the rain and actually resists hydroplaning quite well.

i think the wider tires simply want to stay on top of the water no matter what the tread depth is- there is just more water to move out of the way.

06-08-2020, 06:09 PM	#1
dparm Stop the hate, get a V8 3850 Rep 8,625 Posts Drives: C7 Corvette GS, AMG C63 S Join Date: Jun 2013 Location: Frisco, TX iTrader: (1)	Tread depth versus tire width for wet traction This isn't directly about an M3, but I just ordered a second set of wheels and need to get some tires for street use plus wet track days. I don't have a massive selection of tires, so I am trying to understand some fundamentals of how to maximize wet traction. All else being equal, what will provide better wet traction: a narrower tire or one with deeper tread? In my case, I can get the OEM tire which has about 7.4/32" when new or get a tire slightly wider that has 9 or even 9.5/32". As I understand it, the car has a slightly shallower tread depth when new because it reduces tread squirm and provides better handling -- at the expense of wet traction. __________________ Now: 2017 Corvette Grand Sport, 2021 AMG C63 S sedan Past: 2011.5 M3 sedan ZCP
	Appreciate 0 Tweet Quote

06-09-2020, 01:07 PM	#2
aus Major General 892 Rep 9,032 Posts Drives: Odysse Join Date: Jul 2005 Location: Seal Beach, CA iTrader: (10)	Narrower tire will dig deeper into standing water and have less hydroplaning. Deeper tread will help evacuate the water, so you want both. . __________________ Let me get this straight... You are swapping out parts designed by some of the top engineers in the world because some guys sponsored by a company told you it's "better??" But when you ask the same guy about tracking, "oh no, I have a kid now" or "I just detailed my car." or "i just got new tires."
	Appreciate 0 Quote

06-09-2020, 07:00 PM	#3
Redd Brigadier General 3900 Rep 4,165 Posts Drives: 2010 BMW E92 M3 Dakar Edition Join Date: Jul 2015 Location: Malaysia iTrader: (0)	I think the narrower vs wider argument is moot due to the small range of tire width you have to play with. Going from 265mm down to 245mm isn't going to make a whole lot of difference in terms of cutting thru the water better. You're better off focusing on tread depth (more the better) and most importantly tread design and compound. Tread design and tire compound is the main reason why tires like PS4S do so much better in the wet than other tires. I think if you need a performance tire for street and wet track use, you're not gonna do much better than PS4S.
	Appreciate 0 Quote

06-09-2020, 07:31 PM	#4
roastbeef Lieutenant General 11586 Rep 12,726 Posts Drives: E92 M3 Join Date: Nov 2010 Location: Orange County, CA iTrader: (4)	i'd say narrower would be better. my m3 has 275/295's on it and it tends to dance around in the rain a little bit. it does have a fairly aggressive alignment, but i wear out the inside from camber wear before the tread is done, so they always have good tread. my smart car has 155/60/15's and it handles heavy rain like a champ. cuts through standing water without issue. actaually drives really nice in the rain and actually resists hydroplaning quite well. i think the wider tires simply want to stay on top of the water no matter what the tread depth is- there is just more water to move out of the way. __________________ Instagram; @roastbeefmike
	Appreciate 0 Quote