What Size PSS for OEM 19" Wheels?

[M4TW]

Originally Posted by CanAutM3

I am pretty sure it would.

Thanks bro

At least with myself, I worry about something I call the thermostat phenomenon when it comes to troubleshooting these tires. When it's cold in a room, people tend to ram the control too far to the right and, before long, it's too hot. And so on.

Maybe this is the just right adjustment needed since PSS tires have a pretty good rep as demonstrated by your positive experience with them previously. It is beginning to sound like they were significantly tampered with to get the * designation for the F80/2.

I don't see any difficulty with wearing out my rears to facilitate a change, any concern with mixing them with the specialty fronts, or should they all be changed at once?

[gthal]

Originally Posted by Racer20

Yes, that's exactly what I'm saying. It's not a matter of what I think . . . My background is that I'm a ride and handling engineer and I have done this exact type of tire development in the past at the OEM level. Even something as mundane as a Grand Cherokee has one-off tires. Typically tread design is kept common across a tire model line, but everything else you mentioned is fair game. There are SOME cases where off the shelf tires are used, but overall it's the exception, not the rule.

Automakers make a big deal about "specifically developed" tires because the public doesn't know any better. Just like "low pressure Nitrogen filled gas shocks" . . . EVERY shock made today is filled with Nitrogen. It's just fancy words for marketing.

I am absolutely convinced that the PSS on my Stingray are NOTHING like the PSS on my M4. The traction and heat resistance capability of the tires on the Corvette was much, much better than my M4. Good enough that track specific tires were not important but, IMO, are needed for the M4. The "same" tire on both cars but the performance was very different.

[Racer20]

Originally Posted by M4TW

Thanks bro

I don't see any difficulty with wearing out my rears to facilitate a change, any concern with mixing them with the specialty fronts, or should they all be changed at once?

Maybe.

The handling balance, steering response, and how confident it feels during cornering is highly dependant on the front and rear tires being properly matched for steering response, lateral stiffness, and how they build and lose grip with load and slip angle.

Mismatched tires front to rear CAN cause the car to feel squirmy, vague, or unpredictable, or worse, make it unstable or unsafe to drive at the limit.

So it heavily depends on what BMW changed compared to the off the shelf PSS. It might be absolutely fine. Nobody can know for sure until someone who actually knows how to evaluate these things tries it.

[Racer20]

Originally Posted by gthal

I am absolutely convinced that the PSS on my Stingray are NOTHING like the PSS on my M4. The traction and heat resistance capability of the tires on the Corvette was much, much better than my M4. Good enough that track specific tires were not important but, IMO, are needed for the M4. The "same" tire on both cars but the performance was very different.

Larger tires and a lighter car automatically means the tires will have better cooling capacity, even if everything else was the same.

[gthal]

Originally Posted by Racer20

Larger tires and a lighter car automatically means the tires will have better cooling capacity, even if everything else was the same.

Agreed... except that the difference was, IMO anyway, too substantial to be just the weight. The tires on the Corvette were actually smaller in the front and only 285's in the rear so only nominally different.

Maybe it was a placebo thing but the tires were not getting greasy after 20 minutes sessions whereas the PSS on the M4 are starting to fade in 10 minutes if I'm pushing them.

But you are correct... the extra couple of hundred pounds the M4 carries would make some difference but it is only a couple of hundred pounds at most as the C7 was weighing in in the 3,450-3,500lb range. I personally believe GM's claim that the compound in the PSS used for the C7 was different and closer to an r compound than the regular PSS.

[Racer20]

Originally Posted by gthal

Agreed... except that the difference was, IMO anyway, too substantial to be just the weight. The tires on the Corvette were actually smaller in the front and only 285's in the rear so only nominally different.

Maybe it was a placebo thing but the tires were not getting greasy after 20 minutes sessions whereas the PSS on the M4 are starting to fade in 10 minutes if I'm pushing them.

But you are correct... the extra couple of hundred pounds the M4 carries would make some difference but it is only a couple of hundred pounds at most as the C7 was weighing in in the 3,450-3,500lb range. I personally believe GM's claim that the compound in the PSS used for the C7 was different and closer to an r compound than the regular PSS.

That could very well be. GM tends to push the envelope when it comes to all-out performance. It would not surprise me that the C7 PSS tires are more aggressive than most others.

[Powaup]

So I should buy 2 295 tires for the rear wheels before my current 275s are gone so that i can use the 275s for the front wheels?

What are the cons to having 295 rear wheels? I know I need wider tires but I was thinking 285 rears and 265 front

I don't have spacers and don't plan on lowering the car anytime soon.

I'm currently at 9k miles and have done 1 track day on my current tires, I'll be doing another track day in May and I expect that to be my last one on this set.

[CanAutM3]

Originally Posted by Powaup

So I should buy 2 295 tires for the rear wheels before my current 275s are gone so that i can use the 275s for the front wheels?

What are the cons to having 295 rear wheels? I know I need wider tires but I was thinking 285 rears and 265 front

I don't have spacers and don't plan on lowering the car anytime soon.

I'm currently at 9k miles and have done 1 track day on my current tires, I'll be doing another track day in May and I expect that to be my last one on this set.

As posted in my OP, the cons I see with 295/35R19 in the rear is a non-negligible increase rolling radius over stock and a non-negligible increase in cost compared to the OEM size.

If you plan to track your car, you will very likely wear down your fronts more than the rears. That is what happened to me, I have some cord showing on the outer edges of the front tires. And that is another benefit of the 275/295 /35R19 option. Since I need to replace my fronts anyhow, might as well move the 275 to the front and buy a set of 295s .

If all 4 tires are worn, you have more options available to you. If I were in that situation, I would most likely go with either the 265/285 /35R19 or the generic 255/275 /35R19 setup. They are cost effective, do provide a very decent increase in contact patch width while not increasing the rolling radius too much (or not at all).

[Powaup]

Originally Posted by CanAutM3

As posted in my OP, the cons I see with 295/35R19 in the rear is a non-negligible increase rolling radius over stock and a non-negligible increase in cost compared to the OEM size.

If you plan to track your car, you will very likely wear down your fronts more than the rears. That is what happened to me, I have some cord showing on the outer edges of the front tires. And that is another benefit of the 275/295 /35R19 option. Since I need to replace my fronts anyhow, might as well move the 275 to the front and buy a set of 295s .

If all 4 tires are worn, you have more options available to you. If I were in that situation, I would most likely go with either the 265/285 /35R19 or the generic 255/275 /35R19 setup. They are cost effective, do provide a very decent increase in contact patch width while not increasing the rolling radius too much (or not at all).

Cool, thanks for your advice, do you know why tire rack adds a "Z" in the tire name? ie: 285/35ZR

[CanAutM3]

Originally Posted by Powaup

Cool, thanks for your advice, do you know why tire rack adds a "Z" in the tire name? ie: 285/35ZR

That is the "generic speed rating" for tires approved for over 150mph. The actual speed rating of the PSS is "Y" as shown on the load rating (example: 100Y)

[/// M sa]

I will be installing 295/35/19's rear and 275/35/19's front tomorrow on my OEM wheels. Will chime in with pics later after driving a couple hundred miles to see how the car handles with Comfort, Sport and Sport Plus.

[CanAutM3]

Originally Posted by /// M sa

I will be installing 295/35/19's rear and 275/35/19's front tomorrow on my OEM wheels. Will chime in with pics later after driving a couple hundred miles to see how the car handles with Comfort, Sport and Sport Plus.

Great please do.

Eager to see more pics and driving impressions.

[/// M sa]

Originally Posted by CanAutM3

Great please do.

Eager to see more pics and driving impressions.

Will do

[AWCGROUP]

295/30 and 305/30 almost is the exact oem ride height of the oem 255/35 and 275/35. would this work? or is the front too wide??

[CanAutM3]

Originally Posted by AWCGROUP

295/30 and 305/30 almost is the exact oem ride height of the oem 255/35 and 275/35. would this work? or is the front too wide??

Both would be too wide for the OEM wheels IMO.

295 needs a 10" wide wheel minimum while OEM is 9" in front. 305 needs 10.5" wide wheel minimum while OEM rear is 10".

[AWCGROUP]

a set of rear wheels on the front with 295s would be a nice "square set". hmmm. interesting!!!! 295/30 all around..

[CanAutM3]

Originally Posted by AWCGROUP

a set of rear wheels on the front with 295s would be a nice "square set". hmmm. interesting!!!! 295/30 all around..

You would need wider wheels in front to do that.

[AWCGROUP]

Originally Posted by CanAutM3

You would need wider wheels in front to do that.

that's what I'm saying. a rear wheel set on the front fitted with the same tire as the rear would work

[gthal]

Originally Posted by AWCGROUP

that's what I'm saying. a rear wheel set on the front fitted with the same tire as the rear would work

Offsets of the rear wheels likely wouldn't work in the front.

[CanAutM3]

Originally Posted by AWCGROUP

that's what I'm saying. a rear wheel set on the front fitted with the same tire as the rear would work

Originally Posted by gthal

Offsets of the rear wheels likely wouldn't work in the front.

That would be a good example of an appropriate use of spacers

[/// M sa]

295s and 275s installed rear and front... Drove about 20 miles so far (will post pics over the weekend) and the impression so far is wow! Traction is much better, feed back is night and day and the front gap is filled up pretty well.

Driving Experience with Suspension on:

Sport + with the new set up its a rough ride. Going over bumps are more noticeable.

Sport: Much improved than Sport + and a lot more comfortable ride.

Comfort: Its now my favorite, I will be alternating between Sport and Comfort depending on the day and purpose.

I drove the car hard, went over bumps, took ramps at high speed and I can easily tell the car is more planted than before. The wider look is nice but it still not wide enough lol the car needs 10.5 rears and 10's front in order to make the stance look wide (at least to my taste) but its definitely wider than the 275s rear and 255's front. The tires look bulky (in a nice way). So far I love this choice and will post pics soon

[CanAutM3]

Originally Posted by /// M sa

295s and 275s installed rear and front... Drove about 20 miles so far (will post pics over the weekend) and the impression so far is wow! Traction is much better, feed back is night and day and the front gap is filled up pretty well.

Driving Experience with Suspension on:

Sport + with the new set up its a rough ride. Going over bumps are more noticeable.

Sport: Much improved than Sport + and a lot more comfortable ride.

Comfort: Its now my favorite, I will be alternating between Sport and Comfort depending on the day and purpose.

I drove the car hard, went over bumps, took ramps at high speed and I can easily tell the car is more planted than before. The wider look is nice but it still not wide enough lol the car needs 10.5 rears and 10's front in order to make the stance look wide (at least to my taste) but its definitely wider than the 275s rear and 255's front. The tires look bulky (in a nice way). So far I love this choice and will post pics soon

Thanks for sharing.

You are getting me excited , can't wait to try that setup on my car .

Looking forward to your pics