Need help with tires for 19x9.5" wheels

[SDAMike]

Hi guys, I'm hoping to get some opinions here about what tire set up to go with on a 19x9.5" square set up on my GT. I currently have 285/35 Conti Extreme Contacts on the car and I cant stand the way they feel so I am starting over.

My car came with the black package wheels so I had 255/40/19's from the factory. Im not tuned and dont plan on it until warranty is close to up so I want to keep about the same stock diameter for the speedo.

From what Ive been looking at I'm thinking 275/35's. Thats only .4 tenths shorter than stock. 275/40's are .7 taller than stock. Im lowered so I dont need to fill the wheel wells, plus Im hoping staying with a lower profile might help my turn in.

But where Im getting stuck is how much attention do I need to pay to tread width with a 9.5" wheel?

Also should I run 275's squared or would something staggered be better? Like 255 in the front, 275 in the rear?

What is the ideal summer tire? Ive been leaning towards the Michelin PS4S or the Super Sports. Any thoughts between those 2...or any other good tires to consider?

Appreciate the help!

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[Mach VII]

Just curious as to why you dislike the Conti's? I have them on mine (19x10") and love the way they feel.

 

[NightmareMoon]

I've run a 275/35 before (its been a while). Honestly I'd just run a 285/35 on the 9.5 but switch the brand. The treadwidth fit between 275 and 285 is a very small difference.

The PP1 GTs come with 275/40s on the rear, and a square 275/40 would be fine. 275/35 is fine too.

 

[86pagt]

If your running the black accent package wheels Im pretty sure they are 19x8.5 unless they changed something. The black pp1 rear wheels are 19x9.5

 

[SDAMike]

Just curious as to why you dislike the Conti's? I have them on mine (19x10") and love the way they feel.

Its hard for me to describe, it might be called very "sloppy turn in" ... they feel like they wiggle with any quick steering adjustment / correction or turn, but it takes a second too. At first I thought it was something else but the more I pumped up the tire pressure the more I got rid of that feeling, but riding around at 43+ PSI doesn't make for a nice ride. IMO, I think the sidewall is just too soft to squeeze them on to a skinnier wheel.

I've run a 275/35 before (its been a while). Honestly I'd just run a 285/35 on the 9.5 but switch the brand. The treadwidth fit between 275 and 285 is a very small difference.

The PP1 GTs come with 275/40s on the rear, and a square 275/40 would be fine. 275/35 is fine too.

I was wondering the same too but Im just not sure which brand/model if I stay with the same tire size. Im scared of blowing another 1k and still be disappointed. That why I was thinking of going down a size or going staggered.

I've really been reading into all this trying to figure this out for real lol...
The tires I currently have, have a section width of 11.4" and tread width of 10.3".

The 275/35 (100Y) Pilot Super Sports have a section width of 10.9" and tread width of 9.6"

The 275/35 (96Y) Pilot Sport 4S have the same section width of 10.9" but according to tire rack a 9.1" tread width...(is it just me or does 9.1" tread width seem really small?)

So I was thinking either one of those might be a decent improvement? Sucks they are expensive...but, at least lightweight.

But you are right, I could also look into section and tread widths for other 285/35's also and compare.

If your running the black accent package wheels Im pretty sure they are 19x8.5 unless they changed something. The black pp1 rear wheels are 19x9.5

I have flow formed konigs in 19x9.5. I probably should have just bought wider rims but I was looking for light and they weigh just under 19lbs...but only came in 9.5" wide.

 

[86pagt]

Sorry misunderstood what wheels you were using... I have PS4s that came with the car after 15k I’m very happy with them... currently 255/40 in the front and 275/40 in the rear. I have 2 extra pp1 19x9.5 and I’ll be going 275/40 squared soon.

 

[PP2Newbie]

Wish I could be of help, I'm a 305/30/19 guy myself.

 

[SDAMike]

Sorry misunderstood what wheels you were using... I have PS4s that came with the car after 15k I’m very happy with them... currently 255/40 in the front and 275/40 in the rear. I have 2 extra pp1 19x9.5 and I’ll be going 275/40 squared soon.

No worries at all. Well, if 275/40 is good, cant imagine 275/35 of the same tire would be bad. Here's the question of the hour for me though, I wonder what the tread width is on the factory 275/40 PS4s?

Wish I could be of help, I'm a 305/30/19 guy myself.

Lol, if not on a 9.5", maybe the direction I should have went

 

[MidwayJ]

The 19x9.5 wheels that come with the Ecoboost HPP with handling package have 265/40 tires. I can understand why you would want wider, though.

 

[86pagt]

No worries at all. Well, if 275/40 is good, cant imagine 275/35 of the same tire would be bad. Here's the question of the hour for me though, I wonder what the tread width is on the factory 275/40 PS4s?

 

[NightmareMoon]

Narrower tread widths and shorter sidewalls will reduce cushion and squirm (so that argues for a 275/35). Keep in mind new tires feel squirmy compared to old ones, even the stiff-sidewalled ones because the tread blocks squirm on new tires.

 

[Fly2High]

Which Extreme Contact are you running? There are several.

I found this article that may help:
http://www.tuneruniversity.com/blog/2011/04/wheel-tech-part-ii-size-matters/

I will attempt to summarize some of the points here.

Take the following with a grain of salt. I may sound a bit extreme and am talking mostly at possibly greater amounts than what you did but from the affects you are experiencing, it sounds justified and may explain what you are feeling. Just trying to help here.

According to recommendation charts on the web, I think the 275 is the widest a 9.5" wide wheel can take. I have attached one below. When you use a wider tire, your sidewalls can flex more giving you that squirming feel you are describing. When you turn, you still first get the sidewalls to flex, eventually you will turn enough and then the tire will finally follow. Basically, you went too wide for improving handling. On the other hand, running a narrower tire , within recommendations, which is a 245 or 255 would cause a more twitchy feeling. Any steering input would quickly respond to your input. Of course, some tires can still fit (305/30R19 Cup 2 on a PP2 front wheel : 19x10.5 Et 24 - this is outside the recommendation but still works). You need to go based on the manufacturer's recommendation as to what the min or max width wheel a tire will fit. Just because it will fit doesn't mean it will improve the handling of the car.

Did you also adjust tire pressure? Sure, higher pressures tend to make the suspension feel stiffer but did you also realize that running a bigger tire without a change in weight on it will not necessarily cause the tire to compress and make more contact? You might need less pressure to get additional contact but that might have a negative handling affect. Based on that article, the amount of tire contact is mostly determined by tire pressure and the weight on the tire. Going to a bigger tire will not necessarily get you more rubber contact with the road. If I recall correctly, the 275.40R19 on a PP1 take 33psi while my 305/30R19 only take 32. Not much but there has to be a reason for the difference when a PP1 and PP2 do not differ that much. Sure, they have different springs, magnaride programming, sway bars, etc but the overall weight of the car is the same.

Going bigger than what the chart suggests is tire dependent. Going bigger than the chart will also reduce the actual contact since you are bending the sidewall more so you are not really gaining the full benefit of a wider tire.

Going to wider tires also might not gain you anything in contact patch. What it will do is reorient that patch. Instead of a long and narrow patch that will aid in forward stability/traction, you will shorten and widen that patch. Long patches tend to be better for acceleration and braking while wider ones tend to be better for lateral loads and cornering. What were you looking to improve with wider tires? A wider tire could result in less acceleration and longer braking.

Often a big change in tire size also requires changes in suspension - springs, sway bars, settings, etc. In your case, it is the same for the rear (in a PP1, not a bae GT) but ~ 3/4" wider than the stock fronts. Look at the PP1 and PP2. they changed the springs, sway bars and suspension programming on it. The PP2 also uses a different offset on the front and back wheels. There has to be a reason for it more than it was done to make it fit. I think it was done to improve handling and to accommodate the bigger tires.

Were you looking for more traction? a 6" wide tire (~ 155 ) can handle above 1g of force. Your stock tires, if chosen correctly with the right compound should be able to exceed what the car can do. Sometimes a lack of traction is caused by the road surface, not a tire sizing issue. A buddy of mine who races short track told me that hitting a little sand, loose debris, or even a painted line on the road can significantly alter the level of traction.

That said, I have a set of VMR V710 19X9.5 wheels for my PP2 for winter. they currently take a Blizzak LM-32 275/35R19 (Fr:ET22, Rr: ET45) with no issues that I can see. At the same time, I do not push my car in winter. I run a 305/30R19 on the OEM in summer.

The downside to using a smaller diameter tire is that your speedo will read higher and your odometer will tick over a little faster. If you have a warranty, you are burning it slightly more quickly. In my case, the 275/35R19 is slightly bigger having the reverse affect - logging less miles than have actually occurred there by lengthening my warranty.

 

[FreePenguin]

I have 19x9.5 wheels all around mounted with 285/35/19 dsw6’s just fine

 

[Fly2High]

I have 19x9.5 wheels all around mounted with 285/35/19 dsw6’s just fine

Like I said, some tires can fit a wider range of rims that what is listed on the chart. You DWS 06 can go to a 11" rim. Of course, that doesn't mean it will improve traction, handling and cornering. It just means it will fit. That is car dependent.

Here are the specs from Conti:



Specs for Selected Tire

SIZE​

UTQG​

MAX. LOAD​

MAX. INFLATION PRESSURE​

TREAD DEPTH​

TIRE WEIGHT​

RIM WIDTH RANGE​

MEAS. RIM WIDTH​

SECT. WIDTH​

TREAD WIDTH​

OVERALL DIAM.​

REVS. PER MILE​

COUNTRY OF ORIGIN*​

285/35ZR19 99Y SL​

560 AA A​

1,709 lbs​

51 psi​

10/32"​

28 lbs​

9-11"​

10"​

11.4"​

10"​

26.9"​

772​

SK​

As you can see, the tread width of a 285/35R19 is really 10" or 255mm.

Also, the manufacture listed a 'Measured Rim Width' of 10" which is the designed width of rim this size tire was made for to get these dimensions. It is quite possible that you gained no tread patch width improvement or very little and only increased all you tires by the 2lb difference that a 275/35 would have been. A 275/35 has a tread width of 9.6, a 275/40 has 9.4.


Also, just because the tire can flex to fit a smaller rim doesn't mean you are necessarily increasing your contact patch. The tire, when put on a smaller rim will crown more possibly reducing the contact patch when compared to a smaller width tire..

Also, by going to the smaller diameter tire you affectively increased your final drive and all that goes with that. The PP2 with its smaller diameter tires effectively makes its 3.73 into a 3.94 when compared to a PP1.

 

[SDAMike]

Narrower tread widths and shorter sidewalls will reduce cushion and squirm (so that argues for a 275/35). Keep in mind new tires feel squirmy compared to old ones, even the stiff-sidewalled ones because the tread blocks squirm on new tires.

That's what I was thinking, and really what I'm hoping for... More response and then in turn less tire pressure, then I can turn my shocks back down again too and hopefully it wont be such a punishing ride anymore. (Fingers crossed)

Which Extreme Contact are you running? There are several.

I found this article that may help:
http://www.tuneruniversity.com/blog/2011/04/wheel-tech-part-ii-size-matters/

I will attempt to summarize some of the points here.

Take the following with a grain of salt. I may sound a bit extreme and am talking mostly at possibly greater amounts than what you did but from the affects you are experiencing, it sounds justified and may explain what you are feeling. Just trying to help here.

According to recommendation charts on the web, I think the 275 is the widest a 9.5" wide wheel can take. I have attached one below. When you use a wider tire, your sidewalls can flex more giving you that squirming feel you are describing. When you turn, you still first get the sidewalls to flex, eventually you will turn enough and then the tire will finally follow. Basically, you went too wide for improving handling. On the other hand, running a narrower tire , within recommendations, which is a 245 or 255 would cause a more twitchy feeling. Any steering input would quickly respond to your input. Of course, some tires can still fit (305/30R19 Cup 2 on a PP2 front wheel : 19x10.5 Et 24 - this is outside the recommendation but still works). You need to go based on the manufacturer's recommendation as to what the min or max width wheel a tire will fit. Just because it will fit doesn't mean it will improve the handling of the car.

Did you also adjust tire pressure? Sure, higher pressures tend to make the suspension feel stiffer but did you also realize that running a bigger tire without a change in weight on it will not necessarily cause the tire to compress and make more contact? You might need less pressure to get additional contact but that might have a negative handling affect. Based on that article, the amount of tire contact is mostly determined by tire pressure and the weight on the tire. Going to a bigger tire will not necessarily get you more rubber contact with the road. If I recall correctly, the 275.40R19 on a PP1 take 33psi while my 305/30R19 only take 32. Not much but there has to be a reason for the difference when a PP1 and PP2 do not differ that much. Sure, they have different springs, magnaride programming, sway bars, etc but the overall weight of the car is the same.

Going bigger than what the chart suggests is tire dependent. Going bigger than the chart will also reduce the actual contact since you are bending the sidewall more so you are not really gaining the full benefit of a wider tire.

Going to wider tires also might not gain you anything in contact patch. What it will do is reorient that patch. Instead of a long and narrow patch that will aid in forward stability/traction, you will shorten and widen that patch. Long patches tend to be better for acceleration and braking while wider ones tend to be better for lateral loads and cornering. What were you looking to improve with wider tires? A wider tire could result in less acceleration and longer braking.

Often a big change in tire size also requires changes in suspension - springs, sway bars, settings, etc. In your case, it is the same for the rear (in a PP1, not a bae GT) but ~ 3/4" wider than the stock fronts. Look at the PP1 and PP2. they changed the springs, sway bars and suspension programming on it. The PP2 also uses a different offset on the front and back wheels. There has to be a reason for it more than it was done to make it fit. I think it was done to improve handling and to accommodate the bigger tires.

Were you looking for more traction? a 6" wide tire (~ 155 ) can handle above 1g of force. Your stock tires, if chosen correctly with the right compound should be able to exceed what the car can do. Sometimes a lack of traction is caused by the road surface, not a tire sizing issue. A buddy of mine who races short track told me that hitting a little sand, loose debris, or even a painted line on the road can significantly alter the level of traction.

That said, I have a set of VMR V710 19X9.5 wheels for my PP2 for winter. they currently take a Blizzak LM-32 275/35R19 (Fr:ET22, Rr: ET45) with no issues that I can see. At the same time, I do not push my car in winter. I run a 305/30R19 on the OEM in summer.

The downside to using a smaller diameter tire is that your speedo will read higher and your odometer will tick over a little faster. If you have a warranty, you are burning it slightly more quickly. In my case, the 275/35R19 is slightly bigger having the reverse affect - logging less miles than have actually occurred there by lengthening my warranty.

Thank you for the detailed reply!

I am running the extreme contact sports.

Yeah I get the feeling I went too wide on the tires, and with the wrong brand/style of tire. I could be totally wrong but I dont think I would be having such pronounced wiggle or squirm if I went with a tire with a hard / reinforced sidewall even in the same size. These ECS tires have a very soft side wall. They also are very sticky, so I think the grip really brings out the flex during quick maneuvers.

I wanted to go with wider tires to improve grip, esp. for the rear. In cornering and acceleration. While the stockers weren't terrible, there was definitely room from improvement.

I have played with tires pressures alot on these ECS tires. I started at like 32 psi and slowly kept working my way up on PSI trying to loose the sloppy feeling. It wasnt until I got the tires to around 42-43 PSI and also stiffened up my shocks that I got the response of the car to what I would consider acceptable/predictable. But, now the car rides pretty harsh on certain roads.

FWIW in another thread I made, someone mentioned getting rid of my BMR rear sway bar and going back to OEM or just a PP one. I'm not sure how much that has to do with what Im feeling, but I was debating trying that also.

I found this quote from a motoiq article I read a few days ago:
“For ideal handling: when sizing a tire for a given wheel, I usually target a tire’s TREAD width to be as wide as the WHEEL width, or 0.5” narrower than the wheel width.”
Do you guys think thats a good general rule to stick to in picking new tires?

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