Buying Performance Tires - Best size for 18-inch wheel?

[Sunshine Speed]

Update: I ordered the Michelin Pilot Sport 4S from Costco, size 245/45/18, thanks for helping me choose the size. Total was $940 out the door with tax and installation. I'm planning to ask Costco to fill the new tires with nitrogen, I heard it's better than air. Also I'll try to sell the current stock Michelin Primacy tires on Craigslist for $200 or $300, they have 2000 miles on them. This also might be a good time to buy wheel locks from somewhere. I'll post back here in 2 weeks about how the tires feel compared to stock.

 

[Perry]

Also look at the tread width not the overall size. I've seen several Michelins with different size list the same tread width.

Yes this is strange. According Tirerack, a 265 width Michelin tire has a tread width of 8.7" while a 255 in same tire has a tread width of 9.3". It would seem like the 255 would have a greater contact patch. Why would anyone get the 265 then when it's also 3 lbs heavier?

 

[Xenoilphobe]

Thank you for your feedback! It's quite nice to have someone respond from actual personal/competent performance driving experience.

I'd like to get a set of wheels to use with summer tires (will keep the OEM 18" for the winter) and I was going to pick whatever looks decent as long as it fits and it does the most to quell the understeer. If 275s on 10" fit the front, then that's what I'll do all around. Once I have the new wheels, I'll move on to figuring out what to do about the suspension.

What offsets will you be using front and back and what would you say is an ideal offset/scrub for poised street driving with good cornering feel (again, a la Cayman/M2)? I'm not planning to lower the car or push the wheels out for better looks or anything of that sort. Should I stick with 40 offset and just go 10" wide or are there any benefits to using some other offset?

TIA!

I would read this thread to figure out the best config. Also we have a group buy going on wheels. See my signature if you want to check out some options. 10 wide in the front for a daily driver, might be a little too much without some modifications to the car. One of the best things you can do after buying good tires, is to reduce upsprung weight, car will handle better, steering feel will improve and it will be a blast to drive street or track..

One of the Track Wheel+Tire Setup used by MPP:

• Advan RGIII Wheels
• Front: 19×9 +25
• Rear: 19×10 +35
• Bridgestone RE71R Tires (these are great for track, not so great for a daily driver)
• Front: 245/40/19
• Rear: 275/35/19

Group Buy Poll for Mono-Block Forged Alloy Wheels by Titan 7

 

[Zippy_EV]

Also, how are those front brake pads you have for sale? The description indicates that they are formulated for street driving, which would be exactly what I'm looking for.

I feel that the brakes in the Model 3 are quite weak. It's not that they don't stop the car, they just don't do it too convincingly. Unless I'm imagining it, it feels like the colder they are, the worse they feel and grip. I use low regen but I do have some 800 miles on the car already, so the pads should be well worn in, nonetheless they still feel pretty weak. For now, my big fat Q7 (with OEM Brembos) feels more convincing under braking than the Model 3.

I'd guess the rotor does not make that much of a difference and it's probably all down to the pads. Am I correct in this assessment?
Do you have any measurements of how the car performs (in say straight-line 60-0 braking) with those MPP Page Mill brake pads vs the OEMs? Do they feel better?

TIA!

I just did a track day in the M3P+ completely stock and find the car to be very balanced. I also found the brakes to work perfectly for 20 and 30 minute sessions near 90 deg F ambient. No fade and no fluid boil. It's been more than 10 years since I have driven street tires on the track and the Pilot Sport 4S reminded me why r-compounds are so great. That said the 4S tires were very nice for street tires. The biggest problem the car has is lack of "track mode" Once the system start heating up the power is derated which takes some of the fun away and takes the car from a great performer to a momentum car. Still fun but I miss the power.

For the beginning driver: If the car is understeering then transfer a bit of weight to the front to help the car rotate. (the front will stick better and the back will come around.)

P.S. I've spent a lot of time on tracks and recommend it for everyone. Good times!

 

[Knightshade]

We’re hijacking the thread now. I understand your point but it’s not covering my questions to @MountainPass.

Reductio ad absurdum:
Put a dollop of grease on your brake pads, do a 60-0 test and report back if the stopping distance is the same as before.

This was your literal question-

I'd guess the rotor does not make that much of a difference and it's probably all down to the pads. Am I correct in this assessment?
Do you have any measurements of how the car performs (in say straight-line 60-0 braking) with those MPP Page Mill brake pads vs the OEMs?

My reply directly answered your exact question

It's not down to the rotors or pads. It's down to the tires.

The 60-0 braking test you asked about would produce exactly the same results with OEM pads or any aftermarket pad, or rotor, that fit the car.

Though the pad/rotor changes might well change the "feel", the car would still stop in exactly the same distance on the same tires.

Because the brakes don't stop the car- the tires do.

 

[Knightshade]

Update: I ordered the Michelin Pilot Sport 4S from Costco, size 245/45/18, thanks for helping me choose the size. Total was $940 out the door with tax and installation. I'm planning to ask Costco to fill the new tires with nitrogen, I heard it's better than air.

Air is already 78% nitrogen.

Realistically, nitrogen is very very very marginally "better"- enough that if the tire place offers it free- great. But it wouldn't be worth paying any money at all for in any sort of normal use.

(heavy track use where the tires will see some extreme temps might be another story)

 

[TT97]

This was your literal question-

My reply directly answered your exact question

It's not down to the rotors or pads. It's down to the tires.

The 60-0 braking test you asked about would produce exactly the same results with OEM pads or any aftermarket pad, or rotor, that fit the car.

Though the pad/rotor changes might well change the "feel", the car would still stop in exactly the same distance on the same tires.

Because the brakes don't stop the car- the tires do.

I guess that 18.13 update changed the composition of the tires

 

[Knightshade]

I guess that 18.13 update changed the composition of the tires

No, but it didn't change the pads or rotors either

It changed the ABS calibration- which, obviously, isn't hardware at all.

 

[TT97]

No, but it didn't change the pads or rotors either

It changed the ABS calibration- which, obviously, isn't hardware at all.

Sorry, I do agree with you but I couldn't help myself with the comment. Changing pads and rotors has more to do with that twentieth hard stop than the first one.

 

[TeeEmCee]

...
Because the brakes don't stop the car- the tires do.

Litterally, the first result of a search for “effects of brake pad composition”. It even has the word “science” in the address (so it’s got to be good):
https://www.sciencedirect.com/science/article/pii/S221181281400635X

Now seriously, there’s no need to get worked up over this (or any other topic). We got your point, thank you for making it, we can move on. We’re just trying to collect a few simple consumer-grade pieces of info to help with purchasing decisions in a quest to subjectively improve our rides.

Live and let live!

 

[TeeEmCee]

Air is already 78% nitrogen.

Realistically, nitrogen is very very very marginally "better"- enough that if the tire place offers it free- great. But it wouldn't be worth paying any money at all for in any sort of normal use.

(heavy track use where the tires will see some extreme temps might be another story)

Equally skeptical but I plan to try the N fill-up myself for the following reason:

With the hot (and these days effin’ humid) Texas weather, there’s surely a bunch of water vapor in my tires and, from what I’ve read, it seems to contribute to large swings in cold vs hot tire pressures.

I tried lowering the pressure to around 40 to assess the ride at a more normal pressure and I’ve seen swings of up to 5-6 PSI, as reported by the TPMS. That was enough to have the TPMS bitch about low pressure every time I started the car (I think it starts to complain at 39 PSI) and then shut up after some 10 mins of driving as the tires got up to temp.

The N is supposed to escape through the tire a lot more slowly than oxygen and is said to also exhibit less pressure variance with temperature. That may just be enough to keep the tires at a decent presure, just above the warning threshold. That mkes the N fill-up worth a shot to me. If I knew how to set a different warning pressure or disable the TPMS warning altogether, this would be a non-issue.

 

[Knightshade]

Litterally, the first result of a search for “effects of brake pad composition”. It even has the word “science” in the address (so it’s got to be good):
https://www.sciencedirect.com/science/article/pii/S221181281400635X

Now seriously, there’s no need to get worked up over this (or any other topic). We got your point, thank you for making it, we can move on. We’re just trying to collect a few simple consumer-grade pieces of info to help with purchasing decisions in a quest to subjectively improve our rides.

Live and let live!

..not sure if you didn't read, or didn't understand, your own source.

They don't even mention braking distance, and don't test it in the paper you've linked to at all.

They're mostly measuring wear/sheer strength of the pads of different materials. Certainly service life of brake parts can change with different brake parts- but that's not what you asked about.


I'm not worked up, I'm just correcting what seems to be a misunderstanding of how brakes work, as evidenced by your thinking an upgrade of pads or rotors would change a normal 60-0 braking test.

It's a misunderstanding surprisingly common on car forums (as seen by how many people buy big brake kits who never see the inside of a race track, the main place they're actually at all useful).

Anyway I'd highly recommend this link, written by a very well known brake systems engineer- a guy who has literally written books on the topic, teaches SAE master classes on he topic, and has designed braking systems for major brake and vehicle OEMs...

It explains what each part of the braking system does, and does not do...and ultimately why changing any of those parts won't actually stop your car any shorter. He also explains why you still might wish to change them and what benefits doing so might provide even if a shorter-than-stock stopping distance isn't among them.

GRM Pulp Friction

 

[Knightshade]

Equally skeptical but I plan to try the N fill-up myself for the following reason:

With the hot (and these days effin’ humid) Texas weather, there’s surely a bunch of water vapor in my tires and, from what I’ve read, it seems to contribute to large swings in cold vs hot tire pressures.

I tried lowering the pressure to around 40 to assess the ride at a more normal pressure and I’ve seen swings of up to 5-6 PSI, as reported by the TPMS. That was enough to have the TPMS bitch about low pressure every time I started the car (I think it starts to complain at 39 PSI) and then shut up after some 10 mins of driving as the tires got up to temp.

The N is supposed to escape through the tire a lot more slowly than oxygen and is said to also exhibit less pressure variance with temperature. That may just be enough to keep the tires at a decent presure, just above the warning threshold. That mkes the N fill-up worth a shot to me. If I knew how to set a different warning pressure or disable the TPMS warning altogether, this would be a non-issue.

Consumer reports tested the "it leaks slower" theory a while back..

Over a 1 full year period the air tires list 1.3 psi more than the nitrogen ones (both lost some pressure though).

As to temps- Nitrogen is a gas and is still affected by changes in ambient temperature (about one psi for every 10° Fahrenheit)... it does avoid moisture in the mix though usually that's not going to make a huge difference in street driving- it's usually more relevant for racing tires that'll be run a lot hotter and harder.

So while the nitrogen is better, it's a pretty tiny difference in normal use. If you get it free, or for a couple bucks a tire maybe, see how it does for you- but as I say I wouldn't pay extra for it... and remember any time you need to top off the tire unless you're taking it back and paying for nitrogen, you'll be losing the tiny benefit of it adding air.

 

[TeeEmCee]

I would read this thread to figure out the best config. Also we have a group buy going on wheels. See my signature if you want to check out some options. 10 wide in the front for a daily driver, might be a little too much without some modifications to the car. One of the best things you can do after buying good tires, is to reduce upsprung weight, car will handle better, steering feel will improve and it will be a blast to drive street or track..

One of the Track Wheel+Tire Setup used by MPP:

• Advan RGIII Wheels
• Front: 19×9 +25
• Rear: 19×10 +35
• Bridgestone RE71R Tires (these are great for track, not so great for a daily driver)
• Front: 245/40/19
• Rear: 275/35/19

Group Buy Poll for Mono-Block Forged Alloy Wheels by Titan 7

Thank you, I skimmed through some of that rather long thread and found a bunch of conflicting info.

Some say go 275, others say that 255 is the max that fits in the front. There was one post about offsets that implied that the factory setup has zero scrub radius, which, from the little that I’ve read on the subject, is not typically done or desirable.

Has there been any consensus on what is the max front tire width that would not rub?

Also, when going wider, should one ideally stick with 40 mm offset to preserve the original scrub radius or is some other radius desirable? I’ve seen that the poll skews toward a lower offset, which would increase the scrub radius, likely making it positive. From what I’ve read, a positive scrub radius is generally not desirable in road cars. Why are they skewing lower then?

I feel I’ve read enough on the subject to know that I know nothing and, in the absence of expert guidance, I feel I should probably stick with the defaults (40 offset in this case). Those forged wheels in the poll, assuming good mfg quality, surely look compelling price-wise; I just can’t make an educated choice on size and offset.

I was originally going to get some bigger BBS wheels with the default offset, from the tire rack. They’re quite a bit more expensive, also heavier and just flow-formed vs forged. Surely they’re too much money for what they are (brand premium perhaps). How soon is the first batch of Titan 7 expected? Perhaps I should wait to hear some user feedback before buying any. Are MPP going to trial them?

 

[TeeEmCee]

This also might be a good time to buy wheel locks from somewhere.

Model 3 Wheel Lock Set

 

[TeeEmCee]

Consumer reports tested the "it leaks slower" theory a while back..

Over a 1 full year period the air tires list 1.3 psi more than the nitrogen ones (both lost some pressure though).

As to temps- Nitrogen is a gas and is still affected by changes in ambient temperature (about one psi for every 10° Fahrenheit)... it does avoid moisture in the mix though usually that's not going to make a huge difference in street driving- it's usually more relevant for racing tires that'll be run a lot hotter and harder.

So while the nitrogen is better, it's a pretty tiny difference in normal use. If you get it free, or for a couple bucks a tire maybe, see how it does for you- but as I say I wouldn't pay extra for it... and remember any time you need to top off the tire unless you're taking it back and paying for nitrogen, you'll be losing the tiny benefit of it adding air.

I don’t suppose you know how I can turn off that TPMS warning then? 39-ish min required pressure is ridiculously high.

 

[Knightshade]

I don’t suppose you know how I can turn off that TPMS warning then? 39-ish min required pressure is ridiculously high.

You can't.

All new car models produced after September 2007 are required to have a working TPMS system.

Adding an ability to "turn it off" would defeat that requirement.

I have seen some (bot not all) cars that let you reset the "default" pressure to be different than factory set...but I'm not aware of a way to do that on a Tesla as a consumer (I'd expect a service center could do it though unknown if they're willing to).

 

[kbecks13]

Some say go 275, others say that 255 is the max that fits in the front. There was one post about offsets that implied that the factory setup has zero scrub radius, which, from the little that I’ve read on the subject, is not typically done or desirable.

Has there been any consensus on what is the max front tire width that would not rub?

Also, when going wider, should one ideally stick with 40 mm offset to preserve the original scrub radius or is some other radius desirable?

I'm super curious about this info as well, specifically for the P3D+ with bigger brakes. I know we can fit 19" wheels (with mods for lip) and am now trying to determine the best offset and if i can fit a 10" wide wheel with 275s or should just do 9.5" and 255.

 

[Zippy_EV]

Thank you, I skimmed through some of that rather long thread and found a bunch of conflicting info.

Some say go 275, others say that 255 is the max that fits in the front. There was one post about offsets that implied that the factory setup has zero scrub radius, which, from the little that I’ve read on the subject, is not typically done or desirable.

Has there been any consensus on what is the max front tire width that would not rub?

Also, when going wider, should one ideally stick with 40 mm offset to preserve the original scrub radius or is some other radius desirable? I’ve seen that the poll skews toward a lower offset, which would increase the scrub radius, likely making it positive. From what I’ve read, a positive scrub radius is generally not desirable in road cars. Why are they skewing lower then?

I feel I’ve read enough on the subject to know that I know nothing and, in the absence of expert guidance, I feel I should probably stick with the defaults (40 offset in this case). Those forged wheels in the poll, assuming good mfg quality, surely look compelling price-wise; I just can’t make an educated choice on size and offset.

I was originally going to get some bigger BBS wheels with the default offset, from the tire rack. They’re quite a bit more expensive, also heavier and just flow-formed vs forged. Surely they’re too much money for what they are (brand premium perhaps). How soon is the first batch of Titan 7 expected? Perhaps I should wait to hear some user feedback before buying any. Are MPP going to trial them?

People are choosing lower offsets as they want the wheels/tires to be flush with the fender. We all have different goals. All I care about is the best performance. We do need to know the current scrub radius to properly select a wheel if required to deviate from stock. All I know right now is the performance model has +2mm more scrub radius than the non-performance. As I just completed my second day on track my brain is preoccupied with track setup thoughts.

 

[Shizzrock]

People are choosing lower offsets as they want the wheels/tires to be flush with the fender. We all have different goals. All I care about is the best performance. We do need to know the current scrub radius to properly select a wheel if required to deviate from stock. All I know right now is the performance model has +2mm more scrub radius than the non-performance. As I just completed my second day on track my brain is preoccupied with track setup thoughts.

I would worry more about the camber situation TBH