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Another parameter to look at is wheel diameter. As wheel diameter goes up so does wheel weight, while tire weight drops. They tend to balance out but I think smaller diameter rims with higher profile tires still are lighter than larger diameter rims with low profile tires.
Yup, it's always been a trade-off between aesthetics and performance. I think 21" looks the best unless it's really lowered on 20's, so I made sure so buy a set of one of the three forged 21" OEM wheel designs to keep the weight down when I am running the 21s.
Additonally, a narrower tire will place more surface pressure on the road which may lead to better hyroplane resistance.
I've got a lot of experience in using various tire widths on numerous vehicles and I can assure you that it's wider tires that are more resistant to hydroplaning. This fact is corroborated by tire manufacturers including Pirelli: https://www.pirelli.com/tires/en-us/...y/hydroplaning
A reason that some may feel that narrower tires provide better handling is that they breakaway at lower speeds and that the breakaway can be more predictable and controllable. Wider tires can breakaway at such high speeds that the breakaway can seem overwhelming, uncontrollable and dangerous. For example, I can get my 2022 Cayenne to breakaway fairly easy on its narrower 20 inch winter tires but of course winter tires have less dry road traction anyway. I have never been able to get the Cayenne to breakaway on its wider 21 inch 3-season tires on good quality dry pavement since I can't safely push it that fast on public roads where there is no margin for error. I can however sometimes get the Cayenne on the 21's to breakaway/slide while cornering if the pavement is broken and gravelly.
Another very important aspect is braking. Wider tires provide better braking than narrower tires on both wet and dry roads. My wife's Prius was absolutely scary on its original low rolling resistance tires until I got much wider performance tires for it. The wider performance tires trashed the fuel economy of the Prius but we didn't buy the Prius for that. We bought it because at the time it was the only reasonably small hatchback wagon that was available with driver assistance features such as adaptive cruise control and automatic emergency braking.
Who buys a Porsche looking for fuel economy anyway?
I've got a lot of experience in using various tire widths on numerous vehicles and I can assure you that it's wider tires that are more resistant to hydroplaning. This fact is corroborated by tire manufacturers including Pirelli: https://www.pirelli.com/tires/en-us/...y/hydroplaning
A reason that some may feel that narrower tires provide better handling is that they breakaway at lower speeds and that the breakaway can be more predictable and controllable. Wider tires can breakaway at such high speeds that the breakaway can seem overwhelming, uncontrollable and dangerous. For example, I can get my 2022 Cayenne to breakaway fairly easy on its narrower 20 inch winter tires but of course winter tires have less dry road traction anyway. I have never been able to get the Cayenne to breakaway on its wider 21 inch 3-season tires on good quality dry pavement since I can't safely push it that fast on public roads where there is no margin for error. I can however sometimes get the Cayenne on the 21's to breakaway/slide while cornering if the pavement is broken and gravelly.
Another very important aspect is braking. Wider tires provide better braking than narrower tires on both wet and dry roads. My wife's Prius was absolutely scary on its original low rolling resistance tires until I got much wider performance tires for it. The wider performance tires trashed the fuel economy of the Prius but we didn't buy the Prius for that. We bought it because at the time it was the only reasonably small hatchback wagon that was available with driver assistance features such as adaptive cruise control and automatic emergency braking.
Who buys a Porsche looking for fuel economy anyway?
I appreciate the input based on your experience!
There are many articles and threads discussing hydroplaning and tire width, just do a quick google search for "hydroplaning narrower tires". I agree they seem to be contrary to the Pirelli article but below are a few better sources from that search. There are a lot factors involved but I'll test it out when the wet season approaches.
There is no breakaway on PS4S on a street-driven suburban AWD vehicle, as you mentioned. I chose the tire carefully to not sacrifice grip whether compared to the OE A/S or Summer options. Lighter weight can improve braking performance as well, especially when we are looking at tire weight rotating around the hub and the inertia needed to slow them down. Its likely a minimal difference but may be enough to offset any minor loss in contact patch that is not already made up for by the superior tire compound and design.
Aside from the compound, the intent of this experiment was to eliminate the excess tire bulge and I don't believe that much, if any, true contact patch has been reduced, only the appearance of, due to no sidewall bulge. The cushier sidewall has benefits for some users and the ultimate OEM tire dimension is a compromise for all intended users. I should have measured that contact patch before I took off the old tires, but I will compare to my 21" set; although the sidewall profile diference will throw off the comparison to the 265/45 and 295/40 profiles.
Fuel economy was an added benefit, but was not the main purpose of the experiment. So far, its all positives other than the slight 7mm increase in fender gap and thinner apperance from the front or rear (only compared to the wide OE look, but not too thin, generally). If I do notice any true performance negatives, I will be sure to share them. Knowing PS4S, I will wear these out rather quickly and be onto my next set, probably 255/45 and 285/40. My PS4 SUV set only had about 10K miles before I noticed a degraded ride quality and tracking issues, but awesome tires otherwise if you can get over the harsher ride.
I've got a lot of experience in using various tire widths on numerous vehicles and I can assure you that it's wider tires that are more resistant to hydroplaning. This fact is corroborated by tire manufacturers including Pirelli: https://www.pirelli.com/tires/en-us/...y/hydroplaning
A reason that some may feel that narrower tires provide better handling is that they breakaway at lower speeds and that the breakaway can be more predictable and controllable. Wider tires can breakaway at such high speeds that the breakaway can seem overwhelming, uncontrollable and dangerous. For example, I can get my 2022 Cayenne to breakaway fairly easy on its narrower 20 inch winter tires but of course winter tires have less dry road traction anyway. I have never been able to get the Cayenne to breakaway on its wider 21 inch 3-season tires on good quality dry pavement since I can't safely push it that fast on public roads where there is no margin for error. I can however sometimes get the Cayenne on the 21's to breakaway/slide while cornering if the pavement is broken and gravelly.
Another very important aspect is braking. Wider tires provide better braking than narrower tires on both wet and dry roads. My wife's Prius was absolutely scary on its original low rolling resistance tires until I got much wider performance tires for it. The wider performance tires trashed the fuel economy of the Prius but we didn't buy the Prius for that. We bought it because at the time it was the only reasonably small hatchback wagon that was available with driver assistance features such as adaptive cruise control and automatic emergency braking.
Who buys a Porsche looking for fuel economy anyway?
With traction control I doubt if you coulld get any decent summer tire to break away on dry pavement. That coupled with "four wheel drive" which is actually two axle drive which shares the driving load between front and rear axles...
I found out that this idea was used by Porsche in the Cayenne from 2003-2010. There was a 20" Sport Techno wheel setup that used a 275/40/20 tire on both the rear 20x10 and front 20x9 wheels. This seems odd but if anyone has insight into this decision, that would be interesting to dive into. The 20" tire sidewall has grown since with another leap for the 2024 redesign.
Also, I measured contact patch width to compare the 245/275 to the 265/295 tires and there is about a 1" loss with the narrower tires. I was hoping some of the extra rubber on the OE setup wasnt contacting but turns out there is a contact benefit, with a weight penalty. Keep in mind I am comparing a PS4 SUV tire that has more shoulder to a PS4S that has a tighter sidewall/shoulder design.
Regardless, I have found limits to the OE PS4 All Seasons on my 21" set whereas the skinnier PS4S are holding up well in more aggressive testing. This tells me I am not "behind" in traction vs. the OE offerings due to the compound selection of the narrower tire setup.
I found out that this idea was used by Porsche in the Cayenne from 2003-2010. There was a 20" Sport Techno wheel setup that used a 275/40/20 tire on both the rear 20x10 and front 20x9 wheels. This seems odd but if anyone has insight into this decision, that would be interesting to dive into. The 20" tire sidewall has grown since with another leap for the 2024 redesign.
Also, I measured contact patch width to compare the 245/275 to the 265/295 tires and there is about a 1" loss with the narrower tires. I was hoping some of the extra rubber on the OE setup wasnt contacting but turns out there is a contact benefit, with a weight penalty. Keep in mind I am comparing a PS4 SUV tire that has more shoulder to a PS4S that has a tighter sidewall/shoulder design.
Regardless, I have found limits to the OE PS4 All Seasons on my 21" set whereas the skinnier PS4S are holding up well in more aggressive testing. This tells me I am not "behind" in traction vs. the OE offerings due to the compound selection of the narrower tire setup.
One other item not mentioned are the wheel lug bolts. I just put a set of Titanium bolts on the Macan. Some may say overkill but I just thought I'd mention it. They save 0.5 lb/wheel or 2 lbs total compared to Porsche OEM bolts. They are supposed to be stronger than the steel equivalents and have the added benefit they don't rust and are better at thermal cycling.
Got them from Acer Racing (acerracing.com) in Los Angeles. I bought the 60 degree taper version for the HRE wheels (which do not use the OEM Porsche bolts with the ball seats). Acer has the ball seat Porsche versions as well.
One other item not mentioned are the wheel lug bolts. I just put a set of Titanium bolts on the Macan. Some may say overkill but I just thought I'd mention it. They save 0.5 lb/wheel or 2 lbs total compared to Porsche OEM bolts. They are supposed to be stronger than the steel equivalents and have the added benefit they don't rust and are better at thermal cycling.
Got them from Acer Racing (acerracing.com) in Los Angeles. I bought the 60 degree taper version for the HRE wheels (which do not use the OEM Porsche bolts with the ball seats). Acer has the ball seat Porsche versions as well.
Those are gorgeous and not terribly expensive. Too bad I bought three sets of H&R bolts recently for 10, 15 and 20mm spacers, but I was thinking of trying the rear 20x10 wheels up front and a square 275/40 tire setup. That would just be for looks but at a weight penalty. I would feel a bit better on the weight if I could offset it even a bit with lighter bolts, so I'll keep these in mind for sure!
Those are gorgeous and not terribly expensive. Too bad I bought three sets of H&R bolts recently for 10, 15 and 20mm spacers, but I was thinking of trying the rear 20x10 wheels up front and a square 275/40 tire setup. That would just be for looks but at a weight penalty. I would feel a bit better on the weight if I could offset it even a bit with lighter bolts, so I'll keep these in mind for sure!
Spacers must be the worst at adding unsprung weight. What do yours weigh?
Spacers must be the worst at adding unsprung weight. What do yours weigh?
I think the worst is tires since spacers are at the center of rotation, but fair point, they are a couple pounds for all 4. With the smaller tires, they are needed to complete the look I was going for. All the better reason to save a couple of pounds with the titanium bolts.
The genesis of my project was for looks but had the unexpected outcome of a huge performance increase. I'll take the 28lbs of tire weight savings if it means losing a few pounds of that to spacers to balance looks with performance.
Those are gorgeous and not terribly expensive. Too bad I bought three sets of H&R bolts recently for 10, 15 and 20mm spacers, but I was thinking of trying the rear 20x10 wheels up front and a square 275/40 tire setup. That would just be for looks but at a weight penalty. I would feel a bit better on the weight if I could offset it even a bit with lighter bolts, so I'll keep these in mind for sure!
Yes, they are very nicely CNC machined with cold rolled threads. If you are using even longer bolts for spacers they will save more weight. They also have some very nice PVD coated black Ti bolts if you have black wheels and want the hardware to dissappear.
They also have 5 sided (and Torx heads) which can be used as security bolts which replace the Porsche security anti-theft bolts.
For the 275/40 square setup are you not concerned about too much understeer up front?
Yes, they are very nicely CNC machined with cold rolled threads. If you are using even longer bolts for spacers they will save more weight. They also have some very nice PVD coated black Ti bolts if you have black wheels and want the hardware to dissappear.
They also have 5 sided (and Torx heads) which can be used as security bolts which replace the Porsche security anti-theft bolts.
For the 275/40 square setup are you not concerned about too much understeer up front?
Its nice they have a ton of options. What do they look like on your HREs? I am always up for seeing a set of HREs on a Macan.
I test fit the 20x10 up front and they fit pretty well. I am not sure if it's worth the switch yet but I am not too concerned about understeer for what I use the car for but I see where you are coming from considering the factory setup already leans in that direction. I have an adjustable sway bar and can always play with tire pressures to balance if I go that route.
Its nice they have a ton of options. What do they look like on your HREs? I am always up for seeing a set of HREs on a Macan.
I test fit the 20x10 up front and they fit pretty well. I am not sure if it's worth the switch yet but I am not too concerned about understeer for what I use the car for but I see where you are coming from considering the factory setup already leans in that direction. I have an adjustable sway bar and can always play with tire pressures to balance if I go that route.
I'll see if I can take some photos for you. The look is very subtle. My HREs are a medium anthracite (metallic gray) so there is some contrast with the bolts, but they are buried deep in the socket so are not really obvious. Not like the chrome played bolts HRE sent me with the wheels.
I'll see if I can take some photos for you. The look is very subtle. My HREs are a medium anthracite (metallic gray) so there is some contrast with the bolts, but they are buried deep in the socket so are not really obvious. Not like the chrome played bolts HRE sent me with the wheels.
Very nice, do you have any photos of the entire car with them? Is there an option for fitment or machining to fit the OE center caps?
02-25-2024, 08:52 PM
