325 tires for rear?

[GT350/BT55]

PS4S does grip better than PSS. I drove my GT350 with PSS on Angeles Crest Hwy many times. I would lose a big traction when coming downhill at the turn where there is a big bump. With the new PS4S I go at the same speed if not faster, and the bump does not upset the balance of the car at the same turn.

Angeles Crest is prob the most fun road in the west.
I live on East Coast, but still remember that road well.
I used to go crazy up there on my Suzuki GSX-R when I
was in college (way long ago) in Orange County.

Knee scraping hooliganism all the way.
I am sure a Shelby is super fun, and a whole lot safer.

Ever hit Palomar Observatory road??

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[Stuntman]

PS4S does grip better than PSS. I drove my GT350 with PSS on Angeles Crest Hwy many times. I would lose a big traction when coming downhill at the turn where there is a big bump. With the new PS4S I go at the same speed if not faster, and the bump does not upset the balance of the car at the same turn.

Testing old PSS' to new PS4S on the street is not a valid test.

Most people tend to think Brand X tire is significantly better than their old Brand Y tire (even if X is slower) simply because the difference in grip between and old tire and a new one can be far greater than the actual difference between brand X & Y.

On a racetrack, new for new, off the shelf PSS & PS4S are within a second of each other. If you can feel that on the street, on top of being very reckless, i'm sure you can get hired as a test driver.

 

[Zitrosounds]

A little note on tire sizing. This would apply to anyone with R sizes and planning to run the ps4s which is an overall better tire than the pss. I typically size tires under the same principles so I agree 100%. As did Ford.

On a side bar with Billy (derived from his post), We talked about the 350 MPSS and the new PS4S. After our conversation and his insight, I chose to go with the bespoke MPSS as an alternative to the SC2's on my R wheels. I have a set of 350 MPSS and 350 SC2's ready on the shelf in my garage.

 

[Tony Alonso]

Please keep this thread on topic and use the Ignore User function if you have conflicts. Further bickering will result in account bans and putting people on moderated status.

 

[MrCincinnati]

A little note on tire sizing. This would apply to anyone with R sizes and planning to run the ps4s which is an overall better tire than the pss. I typically size tires under the same principles so I agree 100%. As did Ford.

295/305 30 or 35?

 

[TYAO=RH]

295/305 30 or 35?

A little note on tire sizing. This would apply to anyone with R sizes and planning to run the ps4s which is an overall better tire than the pss. I typically size tires under the same principles so I agree 100%. As did Ford.

Going to resurrect this thread as I saw some very good points made by Billy Johnson's article and his "Public Service Announcement"...I am looking at swapping out the SC2's when I get my R for some PS4S tires (I am going to daily this thing with the stock carbon wheels). I was, up until this point, thinking 305 and 325 setup is my only option for that tire (and any replacement "daily" tire on the R for that matter), but it looks like the recommendation from Billy Johnson and his well written article is to put 295's up front and 305's in the rear...my only question would also be the same as notated above, would you spec the 295/305 setup with the same section width at 30? This all seems to go against the grain of many other threads/tire recommendations I have read on here but makes incredibly good sense from a reliable source.

 

[TYAO=RH]

http://www.motoiq.com/MagazineArtic...LY-select-and-size-TIRES-for-PERFORMANCE.aspx

Billy Johnson's article I am referring to.

 

[JAJ]

Going to resurrect this thread as I saw some very good points made by Billy Johnson's article and his "Public Service Announcement"...I am looking at swapping out the SC2's when I get my R for some PS4S tires (I am going to daily this thing with the stock carbon wheels). I was, up until this point, thinking 305 and 325 setup is my only option for that tire (and any replacement "daily" tire on the R for that matter), but it looks like the recommendation from Billy Johnson and his well written article is to put 295's up front and 305's in the rear...my only question would also be the same as notated above, would you spec the 295/305 setup with the same section width at 30? This all seems to go against the grain of many other threads/tire recommendations I have read on here but makes incredibly good sense from a reliable source.

Yes, he was referring to PS4S 295/30x19 fronts and 305/30x19 rears. They are 11" tread width and 11.5" tread width respectively, the same as the front and rear rim widths on a GT350R, and his article says that's optimum for handling.

 

[tdzee]

Took a while getting thru all the hate mail here to see if anyone brought up another relevant point. Did not see it and I looked only briefly at the long article referenced just above, which may mention this.

Most of the technical part of this discussion centered on the diameter/circumference issue wrt speedo error. That was beat to death and that can apparently be re-calibrated in Forscan for a delta. However, there is another point to consider. That is the electronic nannies. I ran into this on my C5 and I will assume is relevant on this car too. On a C5, they had a 10% (maybe it was 5%, I forget) error band before the nannies kicked in. Therefore, a diameter/circumference change would "use up" some of this deadband prior to the engagement of the nannies. In other words, if you use a different diameter/circumference tire (without recalibrating for this delta), in addition to the speedo error, the nannies will kick in sooner because they are looking for rotating speed deltas between each corner vs what it is expecting based on tire diameter/circumference as supplied. FWIW

 

[JAJ]

...if you use a different diameter/circumference tire (without recalibrating for this delta), in addition to the speedo error, the nannies will kick in sooner because they are looking for rotating speed deltas between each corner vs what it is expecting based on tire diameter/circumference as supplied. FWIW

Some cars have this, but Ford SVT and Ford Performance vehicles don't have this problem. The calibrations of these cars are very tolerant of rotational differences front to rear. This is one of the big differences between FP vehicles and regular Ford Mustang GT's and other regular Fords.

 

[tdzee]

Some cars have this, but Ford SVT and Ford Performance vehicles don't have this problem. The calibrations of these cars are very tolerant of rotational differences front to rear. This is one of the big differences between FP vehicles and regular Ford Mustang GT's and other regular Fords.

OK. Then how do they detect differential slippage at each corner? Most manufacturers use the ABS sensors at each wheel to detect differences in rotational speed for ABS, traction and yaw control. Any why would Ford go to the extraordinary expense of creating a different control scheme for this model than a std Mustang to achieve the exact same result?

 

[JAJ]

Some cars have this, but Ford SVT and Ford Performance vehicles don't have this problem. The calibrations of these cars are very tolerant of rotational differences front to rear. This is one of the big differences between FP vehicles and regular Ford Mustang GT's and other regular Fords.

OK. Then how do they detect differential slippage at each corner? Most manufacturers use the ABS sensors at each wheel to detect differences in rotational speed for ABS, traction and yaw control. Any why would Ford go to the extraordinary expense of creating a different control scheme for this model than a std Mustang to achieve the exact same result?

I can't answer your "how do they do it" question except to say that having switched from a heavily modded 2011 Mustang GT first to a 2014 GT500 and then to a 2016 GT350, it's night-and-day different. It could be as simple as providing more "room" for yaw and other variations before the nannies kick in. The nannies will kick in if you get too far off the reservation, but you don't have to fight them in every corner and you don't have to worry if you switch tire sizes by a couple of sizes.

 

[tdzee]

OK, so your different Mustangs behaved differently. Not surprising given the models you note.

Am not sure if you are referring to this issue specifically on those models, vs those cars in general. I did not say that it would necessarily be a problem, just that it would likely reduce the margin prior to kicking in, in addition to the slight speed error.

 

[Droopy1592]

Ever hit Palomar Observatory road??

20 years ago on a 99 R6.

do the MPS4S even come in our sizes? Last time I checked there was a 305 but not a 295. But that was over a year ago.

 

[crazymayhem]

I went with the 4S in 305/30/19 on all 4 corners with the stock wheels. Fits, works - ive got some tramlining which popped up after the alignment was done when I got the new engine in, but still awesome tires.

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