Square 265/35/19 setup

[rhyary]

I was wondering if anyone tried a square setup of 265/35/19. Since this is available in the R7 or A7 Hoosier, I wonder if that would allowed the car to rotate more compares to 265/35 and 295/30

[tsk94]

Lots and lots of people have ran 275 square, which section width wise in an R7 would be almost identical.

Assuming all things held equal, yes the 265 square setup will rotate better than a 265/295 setup. If the car becomes too loose that can be sorted by changes to sway bars, alignment, ride height and damper settings.

[roastbeef]

Originally Posted by rhyary

I was wondering if anyone tried a square setup of 265/35/19. Since this is available in the R7 or A7 Hoosier, I wonder if that would allowed the car to rotate more compares to 265/35 and 295/30

the reason why most run 275/35/18's is for rotation, good tire meat, and good balance. its a nicely balanced setup for those reasons.

the goal of going square isn't to decrease the rear tire size, its all of the above. if you don't care about the other reasons, then run the staggered 265/295 setup.
the front is going to have the same amount of grip, you're not taking away grip by running a larger rear tire, you're increasing the rear grip over the front. you are simply changing the characteristics of how you might drive the car.

[Richbot]

A 265/35-19 is bit too tall up front. That's why you don't see people trying it, it hits stuff. If you make room for it, I don't see why it wouldn't be a fine way to go.

But if you're making room anyway with hammers and whatnot, why not just run 295/30-19 square

[dparm]

Originally Posted by Richbot

A 265/35-19 is bit too tall up front. That's why you don't see people trying it, it hits stuff. If you make room for it, I don't see why it wouldn't be a fine way to go.

265/35R19 up front is 14mm taller than the OEM 245/35R19 (654.1mm diameter versus 668.1mm).

265 square over a 295/265 setup means you will have less traction at the rear. Also, the smaller tire will overheat faster. Honestly, I wouldn't do it. The M3 is heavy and powerful...give it lots of tire. Are you having problems with understeer right now?

[rhyary]

Originally Posted by Richbot

A 265/35-19 is bit too tall up front. That's why you don't see people trying it, it hits stuff. If you make room for it, I don't see why it wouldn't be a fine way to go.

But if you're making room anyway with hammers and whatnot, why not just run 295/30-19 square

I am already running 265/35/19 in the front.
The question was more about the rear, and in the context of popular option of 275/35/18 square.

In addition, 265/35/19 is the OEM size.

[rhyary]

Originally Posted by dparm

265/35R19 up front is 14mm taller than the OEM 245/35R19 (654.1mm diameter versus 668.1mm).

265 square over a 295/265 setup means you will have less traction at the rear. Also, the smaller tire will overheat faster. Honestly, I wouldn't do it. The M3 is heavy and powerful...give it lots of tire. Are you having problems with understeer right now?

Yes, you can't run a slammed down setup like you can with the front OEM but this is not my thing.

295/30 indeed works well, but same goes to the popular 275/35/18, So rotation aside, why run 275 and not 295? (not counting economics for the moment)

[elim11]

Originally Posted by dparm

265/35R19 up front is 14mm taller than the OEM 245/35R19 (654.1mm diameter versus 668.1mm).

265 square over a 295/265 setup means you will have less traction at the rear. Also, the smaller tire will overheat faster. Honestly, I wouldn't do it. The M3 is heavy and powerful...give it lots of tire. Are you having problems with understeer right now?

True. it is taller. It will rub off the fender liner in the front under compression and full lock turning, depending how low you are.

PS, I used it for street driving only, not for tracking. I rubbed a hole thru the window washer tank on the right side and rubbed spots thru the front liner.

I switched to 265/30/19 with no rubbing issues (street only, not track)

[dparm]

If we keep everything else the same, here are the basic physics. Ignore things like suspension, alignment, driver skill, tread compound, etc.

Oversteer --> add more rear tire (because the rear is losing grip and rotating)
Understeer --> add more front tire (because the front is losing grip and rotating)



When you say you want more rotation, that sounds like you have understeer. (or maybe you just prefer an oversteer-bias, but let's assume you prefer neutral for the sake of argument)

But if we want to go another level deeper, where/when do you want more rotation? A tire's contact patch is static only when you are holding a constant velocity. When you are braking and turning (trail brake), the contact patch in the rear gets small and the contact patch in the front gets bigger. The opposite is true when you are accelerating out of a corner: the rear contact patch grows and the front contact patch shrinks. Throwing a bigger tire may not always correct the problem so then you have to get into things like suspension and alignment. And we haven't even gotten to the part where we talk about different driving techniques. :-)

So...where are you not getting the rotation you want? Corner entry? Mid-corner? Corner exit?

Here is potentially what will happen by simply going to a smaller rear tire: you will get more rotation on corner entry/trail brake scenarios, but as you go to power out of the corner, you won't have the contact patch you need to get back to full throttle fast enough.

[rhyary]

Originally Posted by dparm

If we keep everything else the same, here are the basic physics. Ignore things like suspension, alignment, driver skill, tread compound, etc.

Oversteer --> add more rear tire (because the rear is losing grip and rotating)
Understeer --> add more front tire (because the front is losing grip and rotating)



When you say you want more rotation, that sounds like you have understeer. (or maybe you just prefer an oversteer-bias, but let's assume you prefer neutral for the sake of argument)

But if we want to go another level deeper, where/when do you want more rotation? A tire's contact patch is static only when you are holding a constant velocity. When you are braking and turning (trail brake), the contact patch in the rear gets small and the contact patch in the front gets bigger. The opposite is true when you are accelerating out of a corner: the rear contact patch grows and the front contact patch shrinks. Throwing a bigger tire may not always correct the problem so then you have to get into things like suspension and alignment. And we haven't even gotten to the part where we talk about different driving techniques. :-)

So...where are you not getting the rotation you want? Corner entry? Mid-corner? Corner exit?

Here is potentially what will happen by simply going to a smaller rear tire: you will get more rotation on corner entry/trail brake scenarios, but as you go to power out of the corner, you won't have the contact patch you need to get back to full throttle fast enough.

All true.
I am all set with 295/30/19.

I was just thinking that if 275 square is so popular then I should try square.

I tried 275/30 front, 275/35 rear and it wasn't bad. But I can't do that with R7

So if I wanted to try R7 square, the closest I can do is 265/35.

But I am really happy with 295/30/19 RR and I have enough inventory from a good eBay deal for $200/tire 2018 RR so perhaps this test will have to be done by someone else.

[rhyary]

Originally Posted by elim11

True. it is taller. It will rub off the fender liner in the front under compression and full lock turning, depending how low you are.

PS, I used it for street driving only, not for tracking. I rubbed a hole thru the window washer tank on the right side and rubbed spots thru the front liner.

I switched to 265/30/19 with no rubbing issues (street only, not track)

My fender liners are in bad shape from all my experiments. I am still hoping to settle on a setup I can live with, then replace all the liners.

Looks familiar?
This is from Turn 17 at NYST. The driver side looks fine.

[dparm]

Originally Posted by rhyary

All true.
I am all set with 295/30/19.

I was just thinking that if 275 square is so popular then I should try square.

I tried 275/30 front, 275/35 rear and it wasn't bad. But I can't do that with R7

So if I wanted to try R7 square, the closest I can do is 265/35.

But I am really happy with 295/30/19 RR and I have enough inventory from a good eBay deal for $200/tire 2018 RR so perhaps this test will have to be done by someone else.

275 square is done for cost and tire choice reasons. You would need to adjust your driving style a bit to account for a little less width out back. Everyone's priorities are different.

[elim11]

Originally Posted by rhyary

My fender liners are in bad shape from all my experiments. I am still hoping to settle on a setup I can live with, then replace all the liners.

Looks familiar?
This is from Turn 17 at NYST. The driver side looks fine.

Yep that's about right