Dark Grey Turbines

[HankLloydRight]

ust to clarify the miscommunication. With the Tesla S factory staggered setup the tires are 245/35R21’s fronts and 265/35R21’s rears (245mm and 265mm tread-width). So there is more rubber and width on the road (the definition of contact patch

Well, the difference is questionable/marginal. While the 265mm tires are 8% wider than 245mm, there's only a 4% increase in total contact patch area. The contact patch width is larger, but the length is shorter for the 265s. The wider you go with tires, the shorter the length of the contact patch gets, since the contact patch area is roughly calculated by the weight of the car times the PSI in the tire (among other factors, too). If you put super wide 330mm tires on the car, you're not going to get a big increase in the contact patch size, as the length will continue to shorten as the width increases.

The difference in sidewall is just 7mm, or about 1/4". Again, marginal and I would challenge anyone to be able to visually tell the difference (from 5 feet or more away) between two Teslas, on with staggered rears, and another without.

My first Model S P85+ had the staggered setup, which I had driven about 10k miles on. I swapped the rears out with 8.5" rims and 245mm tires (same brand/model), and could never, ever notice a difference in handling. The increased performance of the Performance Plus (+) suspension is from the actual suspension, not the staggered tires. I then ditched the crappy stock Michelin PS2s for the Hankook Ventus V12 evo2s, and never looked back. Simply changing the tires out had a HUGE difference in handling, noise, comfort, and performance.

My other car is a E39 M5 with 120k miles on it, so I know how performance sedans are supposed to handle. And the staggered rims offer exactly ZERO performance benefits but they do have several downsides, as previously mentioned.

 

[Sunshine State]

Well, the difference is questionable/marginal. While the 265mm tires are 8% wider than 245mm, there's only a 4% increase in total contact patch area. The contact patch width is larger, but the length is shorter for the 265s. The wider you go with tires, the shorter the length of the contact patch gets, since the contact patch area is roughly calculated by the weight of the car times the PSI in the tire (among other factors, too). If you put super wide 330mm tires on the car, you're not going to get a big increase in the contact patch size, as the length will continue to shorten as the width increases.

The difference in sidewall is just 7mm, or about 1/4". Again, marginal and I would challenge anyone to be able to visually tell the difference (from 5 feet or more away) between two Teslas, on with staggered rears, and another without.

My first Model S P85+ had the staggered setup, which I had driven about 10k miles on. I swapped the rears out with 8.5" rims and 245mm tires (same brand/model), and could never, ever notice a difference in handling. The increased performance of the Performance Plus (+) suspension is from the actual suspension, not the staggered tires. I then ditched the crappy stock Michelin PS2s for the Hankook Ventus V12 evo2s, and never looked back. Simply changing the tires out had a HUGE difference in handling, noise, comfort, and performance.

My other car is a E39 M5 with 120k miles on it, so I know how performance sedans are supposed to handle. And the staggered rims offer exactly ZERO performance benefits but they do have several downsides, as previously mentioned.

The contact patch is shorter? You are just pulling the 4% number out of thin air, it is incorrect BS and I’ll call you on that. The 265 is just over 8 percent wider and would still have an 8 percent larger contact patch. You were close on one thing but it is not the psi in the tire but rather the load pounds per square on the tread surface touching the road surface. If you are getting down to fractions of a percentage other factors have a greater impact on the difference in length. If you get down to such a small difference you can certainly say it makes more of a difference in contact patch length by varying the tire pressure by 1-2 psi, just the temperature of the tire, the age and brand of the tire will change the length, tread wear will change it because of the diameter change but none of these are noticeable with the naked eye at any distance. There are clearly advantages and disadvantages of staggered tire setups but the difference in a street car is not a large one unless in a higher torque/hp car like a P100DL in launch mode where the car is limited by four wheel traction under hard acceleration. The E39 M was a good large sedan and it paved the way for new M cars with their incredible track performance. I have been fortunate to attend many M performance track days at Miami International and PB International Speedways and have been able to compare all the new M cars back to back on the Miami high banks, auto-cross track and dragstrip. If you like your M5 you would be very impressed at the level of M performance they build today. As far as what you call "crappy" Michelin PS2 tires you should not compare old, dry, worn, PS2 tires to new Hankook V12 tires, try them both new back to back to make a educated choice. The Hankook V12 tires are much cheaper and not a bad tire, I bought V12’s for one of our S’s because of the price advantage, and with the V12’s harder compound they last longer. The PS2 is a softer compound tire and clearly a better performance tire but for bang for the buck you don’t need the PS2 track performance on a Tesla driven on the street, the V12 will get the job done on a budget.

 

[HankLloydRight]

There are clearly advantages and disadvantages of staggered tire setups but the difference in a street car is not a large one unless in a higher torque/hp car like a P100DL in launch mode

Again, ask anyone who knows, staggered tires do not give you increased forward traction, say, in launch mode. I'm not sure anyone would dare try launch mode while turning the car. They really only provide additional lateral grip in cornering due to the rubber differences front to rear. People who track cars usually go with a square setup anyway so the traction is equal in all four corners and the fronts don't break free before the rears. Staggered setups are really just for show/ego, and nothing more.

The contact patch is shorter? You are just pulling the 4% number out of thin air, it is incorrect BS and I’ll call you on that. The 265 is just over 8 percent wider and would still have an 8 percent larger contact patch.

Nope.

Go here: BND TechSource - Tire Data Calculator and see for yourself.

All other factors being equal (temp, pressure, speed, etc), the contact patch width is 233mm vs 246mm, the length is 110mm vs 109mm, and the overall contact patch area is 257cm2 vs 269cm2 (a 4% difference)

 

[HankLloydRight]

As far as what you call "crappy" Michelin PS2 tires you should not compare old, dry, worn, PS2 tires to new Hankook V12 tires, try them both new back to back to make a educated choice.

I've driven on new PS2s and they still suck. They're noisy and non-compliant. They just have great marketing at Michelin to make people believe they're great tires, and they charge extra for that. I also bought two new PS2s that developed sidewall bulges within 5k miles (not due to road impacts). Crap tires.

 

[Sunshine State]

Go here: BND TechSource - Tire Data Calculator and see for yourself.
All other factors being equal (temp, pressure, speed, etc), the contact patch width is 233mm vs 246mm, the length is 110mm vs 109mm, and the overall contact patch area is 257cm2 vs 269cm2 (a 4% difference)

Hmmm, You are comparing a 96Y and a 101Y rating tire which is a bit misleading and manipulated the results as there are tires made with similar load ratings, (your Hankooks as an example). That simple calculation website uses the max weight rating on the tire to calculate the contact patch but can’t take the actual load on each tire into consideration because it is specific to each car. With equal tire load ratings the contact patch is 14 percent larger on a 265 comparing to a 245. Here is the difference in load rating, 96Y (1565 lbs) and a 101Y (1919 lbs). Where the higher load index 265 tire has the advantage is under acceleration where there is significant weight transfer to the rear and the load on the rear tire approaches its maximum and the larger contact patch has a significant advantage. FYI, your Hankook tire is available in a 275/30R21, it has the matching rolling diameter to a 245/35R21 and has a load rating of 98Y, plus has a 14 percent larger contact patch. I actually ordered a pair of the Hankook 275’s and the matching 245’s but then after consideration opted against the rear 275’s and installed 4 of the V12 245’s due to range concerns. I believe that one of the main factors in the range decreases when running the 21’s versus the 19’s is due to the higher performance PS2’s with sticky tread compound and higher friction and rolling resistance which was a consideration when installing the Hankook tires.

 

[HankLloydRight]

Hmmm, You are comparing a 96Y and a 101Y rating tire. That simple calculation website uses the max weight rating on the tire to calculate the contact patch but doesn’t take the load on each tire into consideration

In fact it does take the actual corner load into account in the 'dynamic input data':

521.5 KG in each corner is based on a curb weight of 4600 lbs.

The grey table above is the 'dynamic output data' it says right there: "(Per Veh. Load & A/P)"

Hmmm, You are comparing a 96Y and a 101Y rating tire.

Yup. In order to keep the 245/265 comparison dead-on accurate, I used the OEM staggered tires that come from Tesla. Both OEM Michelin Pilot Super Sport and the CONTISPORTCONTACT 5P have load ratings of 96Y in the front, and 101Y in the rear.

That's certainly what we are comparing here, no?

and the larger contact patch has a significant advantage.

If you consider 4% larger, sure. I call it marginal with insignificant advantage.

 

[Sunshine State]

Well, the difference is questionable/marginal. While the 265mm tires are 8% wider than 245mm, there's only a 4% increase in total contact patch area. The contact patch width is larger, but the length is shorter for the 265s. The wider you go with tires, the shorter the length of the contact patch gets, since the contact patch area is roughly calculated by the weight of the car times the PSI in the tire (among other factors, too). If you put super wide 330mm tires on the car, you're not going to get a big increase in the contact patch size, as the length will continue to shorten as the width increases.
.

No, read your post. You clearly say as width increases the contact patch length gets shorter. That is absolutely false, compare tires with the same rating, if you compare tires with different load ratings you get incorrect results as it isn’t a true apples to apples comparison. A car under acceleration has significantly greater load on the rear tires than the front and thus how the data on that simple calculator is incorrect. Compare your beloved Hankooks in the sizes that match and fit the Model S that I listed and you can see the error and the 14 percent increase in contact patch even though the rear tires still have the higher load index which would be a disadvantage in the results.

 

[HankLloydRight]

t. You clearly say as width increases the contact patch length gets shorter.

No, what I actually said is that length shortens as width increases, and the data I posted above proves that.

Compare your beloved Hankooks in the sizes that match and fit the Model S that I listed and you can see the error and the 14 percent increase even though the rear still has the higher load index.

There's no 265/35/21 Hankook, only 275/30. So there's no way to make a valid comparison.

Using the Telsa OEM tires (two different brands) seemed to me to make the most sense for a scientific approach to this analysis.

We are comparing the square wheel setup to the staggered setup from the factory. Adding in a non-OEM setup destroys the analysis.

But just for kicks, let's do it anyway.

Here are the inputs for the 245s vs. 275s

And the important part of the outputs:

So with 275s, the contact patch length gets even shorter compared to the 265s:

245: 110mm
265: 109mm
275: 107mm

The contact patch widths:

245: 233mm
265: 246mm
275: 259mm

Hmmmm.. it sure looks like to me the contact patch length decreases as contact patch width increases.

And the contact patch area delta from the 245s:

245: 256.99 cm2 (baseline)
265: 268.39 cm2 (a 4.4% increase)
275: 276.73 cm2 (a 7.68% increase)

So the 275s do provide 7.7% more contact patch area compared to the 245s. Not sure where you got 14% from.

------------------------


And for anyone playing along with the home game, the Hankook Ventus V12 evo2s are exactly half the price of the Michelin PSS, but with more than double the performance (in a square 245 setup):

 

[Sunshine State]

There's no 265/35/21 Hankook, only 275/30. So there's no way to make a valid comparison.
View attachment 298729

The 275/30’s versus the 245/35’s are a valid comparison because they are the same rolling diameter as a stock 245/45R19 or the 245/35R21. As far as saying the car wasn’t designed to use that size tire then by that same standard the "+" wasn’t designed to use 8.5 inch wheels. I have no problem with either because the car can’t tell the difference with either of these scenarios.
Ok, like I had said above unless you factor in tires with a load you are only figuring and comparing what the tire does while sitting in your driveway. Under acceleration there is significant weight transfer to the rear and if you were to figure only a small increase say 1500 lbs total load on the rears with 1000 lbs total load still on the front the results become very apparent. Not that it matters much but the tires are "Y" not "ZR" that you had input. I also compared and added a picture of the same 245 fronts and 245 rears under load you can see those results. If you look at the numbers while driving the contact patch is much larger on the bigger tire and thus greater traction on a car limited by massive torque. It has been a long time since I drove a P85, I know the acceleration is not on the level of the D cars so it may not need the extra grip of the bigger tires if it never activates traction control.
I had already posted the link to the Hankook tires above and agree it is a good budget option for the model S but if you take the time to read the reviews of owners most agree that for the price it is a good tire if you don’t want to spend the money to purchase what I agree are overpriced Michelin or Continental tires

 

[HankLloydRight]

What? You're comparing loaded tires to unloaded tires, which makes absolutely no sense.

OF COURSE LOADED TIRES ARE GOING TO PUT MORE RUBBER ON THE ROAD.

How about comparing loaded 245s against loaded 265s?

As far as saying the car wasn’t designed to use that size tire t

I wasn't saying the car wasn't designed to use that size -- because clearly it is since they put 245/35/21s on P85s, 85s, 60s, etc, and only put 265s on the P85+ and P85D. Tesla also sold bunches of P85D with the Plus+ suspension with non-staggered rims and even 19" rims and all-season tires. The Plus suspension is not about adding 3/4" of width to the tires. It's about firmer, sportier handling.

Not that it matters much but the tires are "Y" not "ZR" that you had input.

Look again. The Hankooks, Conti's and Michelins 245s are all ZR rated.

Now if we actually do an apples-to-apples comparison of 245s vs 265s LOADED with your own parameters:

(BTW, why did you use 36PSI when that's way below the Tesla recommendation of 45PSI for 21" tires?)

Here are the results:

Width: 239mm vs 252mm (5.4% difference)
Length: 141mm vs 140mm (wider tires still have less length)

Total Contact Patch Area: 337.32cm2 vs 352.37cm2 -- oh, would you look at that!

It's STILL only a 4.46% increase in contact patch area.

 

[Sunshine State]

What? You're comparing loaded tires to unloaded tires, which makes absolutely no sense.
OF COURSE LOADED TIRES ARE GOING TO PUT MORE RUBBER ON THE ROAD.

I didn’t compare any unloaded tire to a loaded tire, only the two different setups under load during acceleration, that is the purpose of a tire.
Are you saying that a comparison of why someone would want staggered tires makes no sense?
Do you prefer to compare a tires performance sitting parked in a parking lot? Tesla cars are too heavy to be a handling car but they have excellent straight line performance and thus the fast ones can take advantage of higher levels of traction. The quickest Model S cars recorded on the track have been with the staggered setup.
I posted the comparison of 245 fronts and 245 rears under load and acceleration, plus also staggered matching 245 fronts and 275 rears under load during acceleration. You have to compare both charts to see the difference. It’s doesnt get much clearer than that. You keep posting pictures of the chart with the front and rear tires under the same load. Under hard acceleration the rears have even greater loading than I had entered in for comparison. Even if the car had perfect 50/50 weight distribution, which it doesn’t, it would only be 50/50 at a steady cruising speed and if that was the case tire performance is then irrelevant. It just demonstrated the difference and advantage of the staggered setup on a car limited by traction. I would think the rear wheel drive only S P85 would have enough power to activate traction control under acceleration but if you say it doesn’t I’ll accept that. No disrespect intended but if you still can’t understand the advantage then I guess ignorance is bliss.

 

[HankLloydRight]

In both your analyses, Tire #1 is unloaded, and Tire #2 is loaded.

If you want to compare loaded to loaded, wouldn't the corner weight be the same for both?

What you're doing is front to rear under acceleration, and probably only for a RWD vehicle.

340kg is equivalent to a total 1500 pound load (Front).
608kg is 2,675 pound load (rear).

You're losing track of what my original point was, and remains:

Staggered tires do NOT add any significant amount of rubber or traction... but now I'll also add -- under any conditions.

I am NOT comparing front tire traction to rear tire traction under acceleration.

. The fastest Model S cars recorded on the track have been with the staggered setup.

Correlation does not imply causation - Wikipedia

Also, that is at the extreme of performance, which as I said in my original post is the only time you might see a marginal performance difference with staggered rims.

 

[Sunshine State]

In both your analyses, Tire #1 is unloaded, and Tire #2 is loaded.

View attachment 298769

If you want to compare loaded to loaded, wouldn't the corner weight be the same for both?

What you're doing is front to rear under acceleration, and probably only for a RWD vehicle.

340kg is equivalent to a total 1500 pound load (Front).
608kg is 2,675 pound load (rear).

You're losing track of what my original point was, and remains:

Staggered tires do NOT add any significant amount of rubber or traction... but now I'll also add -- under any conditions.

I am NOT comparing front tire traction to rear tire traction under acceleration.



Correlation does not imply causation - Wikipedia

Also, that is at the extreme of performance, which as I said in my original post is the only time you might see a marginal performance difference with staggered rims.

You had said "exactly ZERO performance" benefit to the staggered setup. With rear weight transfer bias difference is greater than 1500 versus 2675 but I used those numbers to so as not to show any bias in my favor. The AWD versus RWD question is not relevant at all. I added the non staggered chart to show the loaded 245’s also. The front to rear bias is never the same and certainly not 50/50. I was only talking about acceleration as that is Tesla’s specialty. If you are talking about cornering loads under hard braking in a turn the front outside tire is under high loading and exiting a turn under full power the outside rear is under high loading. The misconception about stiff suspension being the same as good handing is when someone looks at a skid pad chart and thinks that is the same as real world handing. Larger/stiffer stabilizer bars and less compliant bushings lowers vehicle lean and decreases weight transfer to the outside tire in a turn. Lean in a turn not only changes loads but changes the suspension geometry including the angle of camber which lessens the contact patch area. In the real world with less than perfect road surfaces stiffer suspension actually increases dynamic loading on tires and causes a tire nearing its peak limits to loose traction. In road racing during wet weather conditions teams will unpin stabilizer bar links to create a more supple suspension to lower dynamic loading and prevent stability loss in corners. A driver who thinks a car that rides stiff is a handling car is likely a driver who doesn’t understand what it takes to be a good handling car. No Tesla car is much of a performance handling car and my discussion of tires on a Tesla really only centers around acceleration.

 

[HankLloydRight]

You had said "exactly ZERO performance" benefit to the staggered setup.

Well, I also quickly clarified that only under extreme performance and handling would the staggered tires show a marginal difference. For everyday, street-legal driving, the staggered tires will not have any performance benefit.

blah blah blah

Thanks for the lecture. Nobody is arguing any of those tangentially relevant points.

Bottom line is that given two tires, one 245/35/21 and one 265/35/21 in the same position/loading/turning/inside/outside/whatever, the difference is still marginal. For anyone buying a P85+, P85D or even a P100DL, staggered rims/tires will not have any noticeable effect on driving, handling, or performance. They will have an effect on your ego and wallet.

 

[Racerx22b]

All I've learned by coming here is that some people are REALLY into tire stats! Holy Cow!!

Jason

 

[Sunshine State]

Well, I also quickly clarified that only under extreme performance and handling would the staggered tires show a marginal difference. For everyday, street-legal driving, the staggered tires will not have any performance benefit.



Thanks for the lecture. Nobody is arguing any of those tangentially relevant points.

Bottom line is that given two tires, one 245/35/21 and one 265/35/21 in the same position/loading/turning/inside/outside/whatever, the difference is still marginal. For anyone buying a P85+, P85D or even a P100DL, staggered rims/tires will not have any noticeable effect on driving, handling, or performance. They will have an effect on your ego and wallet.

They will have a effect on your wallet, agreed. In normal day to day "street legal driving", no noticeable performance effect agreed. My only reason for wasting so much time was arguing the “Zero" performance, with only disadvantages claim. Last points though, it is not hard to tell the difference while following a car with 245’s versus 265’s, they both appear to be too small on a car as wide as the Model S. One of the reasons to own a Tesla is vanity and people spend money for that reason. The existence of P cars have little point in day to day "street legal driving"

 

[HankLloydRight]

The existence of P cars have little point in day to day "street legal driving"

Not to start another whole thing, but I actually enjoy the snot out of the P in my P85D.. yes, in street legal driving.

Mostly I-95 on-ramps.

 

[Sunshine State]

Not to start another whole thing, but I actually enjoy the snot out of the P in my P85D.. yes, in street legal driving.

Mostly I-95 on-ramps.

I prefer P cars myself. To take advantage of the difference of the P over the abilities of an S60 are mostly in off the line acceleration. Utilizing the difference between the two can be viewed as “unsafe acceleration", can be cited and is a violation of traffic law. It is a subjective judgement and often viewed as a bs ticket but non the less not legal and something that can receive a warning or ticket. Sometimes it is best to as yourself would I do this if next to a patrol car to answer the question if it is street legal driving. If you ever have used launch mode and were not on a track chances are it would be viewed as very questionable.

 

[HankLloydRight]

I don't do 'insane' accelerations from a stop light or similar. That's why I said 'I-95 on ramps' -- around here, traffic (when it's moving, that is) is averaging 70mph, so if you don't accelerate like that on an on ramp, it's much harder to merge. As evidenced in 50% of the time there's someone "of advanced years" in front of me who doesn't know how to do a high-speed merge, and farks it up for everyone behind them. No LEO is going to give me a warning or ticket for accelerating onto the highway.

 

[Sunshine State]

I don't do 'insane' accelerations from a stop light or similar. That's why I said 'I-95 on ramps' -- around here, traffic (when it's moving, that is) is averaging 70mph, so if you don't accelerate like that on an on ramp, it's much harder to merge. As evidenced in 50% of the time there's someone "of advanced years" in front of me who doesn't know how to do a high-speed merge, and farks it up for everyone behind them. No LEO is going to give me a warning or ticket for accelerating onto the highway.

That is my point, merging is a strong point of any Tesla. Realistically it’s well documented that the biggest difference in acceleration of the P cars and non P cars is almost exclusively in the immediate off the line acceleration, after 20 mph or so the difference is minimal in comparison to the launch difference. Last week we did a 20 mph and up rolling speed comparison between a S90D in "Standard" acceleration versus a P90DL in "Sport" (the one step below Ludicrous). I was surprised to find out the S90D has a slight acceleration advantage over an S P90DL in the Sport setting. The P90DL then had about the same slight advantage over the 90D once the P90DL was in Ludicrous. My point is someone can enjoy the heck out of their Tesla but unless they are in a launch the difference in acceleration is so small you need electronics to measure the difference or it’s mostly the psychological effect of the emblem. Ask almost anyone driving a 60, 70 or 75 if their car is fast and whether their car is fast enough for merging in traffic, most owners are impressed with their Tesla’s power and if they have any difficulties merging in traffic it isn’t their cars fault.