Does anyone have experience dropping from 19" wheels back to 18"?
05-06-2014, 07:57 PM
#1
Pro
Thread Starter
Does anyone have experience dropping from 19" wheels back to 18"?
I bought my car with 19" Antera rims and I've been contemplating dropping back to the stock 18" size for a while. I love the look of my wheels but my preference would have been to stick with wheels designed for the car.
My car is a DD lowered with H&R coilovers and the ride is pretty harsh. I also track the car occasionally and I assume the 18" wheels would handle a little better with a little more sidewall. At the moment I'm running 295r30 Michelin PSS tires.
My goal would be to get a little more sidewall to make the daily drive a little less harsh and allow me to cross train tracks at a reasonable (but low) speed :-)
And hopefully make the car a little more fun on the track.
Does anyone have any experience going back from 19" rims to the stock 18"s? Was it worth it? How did it change the driving experience?
My car is a DD lowered with H&R coilovers and the ride is pretty harsh. I also track the car occasionally and I assume the 18" wheels would handle a little better with a little more sidewall. At the moment I'm running 295r30 Michelin PSS tires.
My goal would be to get a little more sidewall to make the daily drive a little less harsh and allow me to cross train tracks at a reasonable (but low) speed :-)
And hopefully make the car a little more fun on the track.
Does anyone have any experience going back from 19" rims to the stock 18"s? Was it worth it? How did it change the driving experience?
05-06-2014, 09:15 PM
#2
Rennlist Member
How do the 295/30s clear in the rear? I've got 19's as well but with 275/30s. If I keep the 19s I want to go that size in the future. I'm also contemplating 18" wheels because the track worthy tires are much cheaper in 18". I'll watch this thread with interest as well.
05-06-2014, 09:35 PM
#3
Pro
Thread Starter
No problems at all. Actually I had previously been running 315/25s in the rear which are huge. But that is with 11" rims and they stick out a little more than they should. This is on a 996.2 which may have a little more room than the 996.1.
Last edited by kgoertz; 11-30-2014 at 11:43 PM.
05-07-2014, 08:04 AM
#4
Three Wheelin'
Yes. Went from 19" 997 Turbos to 18" Turbo Twists. Car is lowered with H&R's. I like it better in terms of looks, but also went to skinnier rears, so not sure how it would do on the track.
2002 Turbo - Basalt Black Metallic / 2003 Carrera 4S - Speed Yellow / 1955 356 Continental 1500 - Rust Red
2002 Turbo - Basalt Black Metallic / 2003 Carrera 4S - Speed Yellow / 1955 356 Continental 1500 - Rust Red
05-10-2014, 10:52 PM
#5
Pro
Thread Starter
I still haven't reached a conclusion on this. I am considering a used set of stock 18" Sport Techno rims to replace my 19" Anteras.
The rear tires on the 18" rims are 295 30r18 which have the same sidewall height as my current 295 30r19s.
The front tires on the 18" rims are 225 40r18 which have a slightly higher sidewall then my current 235 35r19 but the difference is only 0.3inches (3.5 inch vs 3.2 inch).
I have read lots of posts here indicating that the handling 'performance' on 18" rims is much better than 19" but I'm struggling to understand why. The sidewall isn't significantly different (noting that the rear tires above are slightly larger than stock). The wheels obviously have a larger diameter which would change the effective gear ratio slightly but that shouldn't impact cornering. The weight of the tires is essentially the same (comparing on Tire Rack) and the weight difference between the rims is probably closely related to the change in diameter which is only ~5%.
So having a slightly larger sidewall on the 18"s on the front would likely have a slight reduction in harshness and possibly a little better grip when corning but it doesn't seem significant. The rears are almost the same other than a larger diameter wheel and a higher rotational intertia.
But enough to be noticeable? I'd like to think that dropping to 18"s would make the car a little easier to drive as a DD and possibly a little better on the track. But it is hard to believe there is enough of a difference to be that noticeable. Any thoughts?
The rear tires on the 18" rims are 295 30r18 which have the same sidewall height as my current 295 30r19s.
The front tires on the 18" rims are 225 40r18 which have a slightly higher sidewall then my current 235 35r19 but the difference is only 0.3inches (3.5 inch vs 3.2 inch).
I have read lots of posts here indicating that the handling 'performance' on 18" rims is much better than 19" but I'm struggling to understand why. The sidewall isn't significantly different (noting that the rear tires above are slightly larger than stock). The wheels obviously have a larger diameter which would change the effective gear ratio slightly but that shouldn't impact cornering. The weight of the tires is essentially the same (comparing on Tire Rack) and the weight difference between the rims is probably closely related to the change in diameter which is only ~5%.
So having a slightly larger sidewall on the 18"s on the front would likely have a slight reduction in harshness and possibly a little better grip when corning but it doesn't seem significant. The rears are almost the same other than a larger diameter wheel and a higher rotational intertia.
But enough to be noticeable? I'd like to think that dropping to 18"s would make the car a little easier to drive as a DD and possibly a little better on the track. But it is hard to believe there is enough of a difference to be that noticeable. Any thoughts?
05-11-2014, 12:21 PM
#6
The car was set up and tuned with 18" wheels as the +1 option by the factory. Even the aftermarket parts- H+R, etc. likely used 18" wheels as their setup baseline.
That means everything from dampers and body structure rigidity were tuned to have a certain amount of sidewall give, lateral grip, etc.
Likely, the most important difference is weight. 19's are probably 5-10lbs a corner heavier than equivalent 18's. That means damping is likely off with 19's, and most would notice a difference in acceleration. 19's are like installing a heavier flywheel...
That means everything from dampers and body structure rigidity were tuned to have a certain amount of sidewall give, lateral grip, etc.
Likely, the most important difference is weight. 19's are probably 5-10lbs a corner heavier than equivalent 18's. That means damping is likely off with 19's, and most would notice a difference in acceleration. 19's are like installing a heavier flywheel...
05-11-2014, 02:06 PM
#7
Pro
Thread Starter
I have read many posts indicating that the 996 was set up with 18" wheels therefore it handles better. But very little real data or first-hand opinions.
The sidewall between the 18" wheels and 19" is either the same (3.5") or within 10% depending on the tire choices.
Tirerack indicates that the weights of the tires on the same for 18" and 19" at least for the 295/35ZR18 and 295/35ZR19 Michelin Pilot Sport tires (28 pounds).
Stock 19" rims appear to be slightly heaver than 18" but the much bigger factor is the design of the wheels. A good summary is here: http://www.944racing.de/wheelweights.php
The 18x11 Sport Techno rims weigh 11.9KG (26 pounds) which is heavier than most of the afterweight 19" rims although it is really hard to find the weight of various rims. I was looking at Victor, OZ. For example OZ Ultraleggera HLT in 19x11 weigh 24 pounds.
So the sidewalls are almost the same, the weights of the tires are the same, and the weights of aftermarket 19"s are usually lower than stock 18"s.
So has anyone tried 18 vs 19" rims on the same car and could tell the difference in handling both as a DD and track?
The sidewall between the 18" wheels and 19" is either the same (3.5") or within 10% depending on the tire choices.
Tirerack indicates that the weights of the tires on the same for 18" and 19" at least for the 295/35ZR18 and 295/35ZR19 Michelin Pilot Sport tires (28 pounds).
Stock 19" rims appear to be slightly heaver than 18" but the much bigger factor is the design of the wheels. A good summary is here: http://www.944racing.de/wheelweights.php
The 18x11 Sport Techno rims weigh 11.9KG (26 pounds) which is heavier than most of the afterweight 19" rims although it is really hard to find the weight of various rims. I was looking at Victor, OZ. For example OZ Ultraleggera HLT in 19x11 weigh 24 pounds.
So the sidewalls are almost the same, the weights of the tires are the same, and the weights of aftermarket 19"s are usually lower than stock 18"s.
So has anyone tried 18 vs 19" rims on the same car and could tell the difference in handling both as a DD and track?
Trending Topics
05-11-2014, 02:52 PM
#8
Rocky Mountain High
Rennlist Member
Rennlist Member
I do not have objective data to share with you. All I can offer is my opinion. My thoughts are as follows:
For the vast majority of drivers in the vast majority of situations, you won't be able to tell the difference. As you point out, the wheel and tire combinations that you're comparing are pretty similar.
One thing to consider though is that even though the sizes are very close in terms of overall construct diameter, the distribution of the weight is different. The larger diameter of the 19" wheel means that the weight of the construct is further from the center of rotation than it is in the smaller wheel. Metal weighs more than rubber, and even if you assume that the rubber weighs the same in either construct, that weight is slightly further from the center of rotation. As a result of this change in weight distribution, the gyroscopic stabilization forces in the larger construct are higher. This means that the larger construct requires more force to achieve comparable results in braking and steering compared to the smaller construct. It also means that greater forces are transmitted to the suspension components of the vehicle through the increased torque of the wheel/tire construct. These forces increase dramatically in extreme situations, such as track use.
For this reason, Porsche modified the suspension of the 997 vehicles to compared to the 996 vehicles. The 997 was offered from the factory with 19" wheels, and Porsche knew that some people would track their vehicle. The vehicle was designed to withstand the increased forces.
So... will this really matter or will you be able to feel the difference? I have no idea. Many people track these cars with 19" wheels and never report a problem.
Another thing to think about if track use is important to you: consider the wheels and tires used on modern race cars. If you look at a Formula 1 car, you'll see that the wheel diameters are quite small compared to street cars. These cars are designed for optimum performance on the track, and if larger diameter wheels performed better, they would be used by the F1 teams.
Perhaps you should conisder a set of track wheels and keep your street wheels if you really like them.
For the vast majority of drivers in the vast majority of situations, you won't be able to tell the difference. As you point out, the wheel and tire combinations that you're comparing are pretty similar.
One thing to consider though is that even though the sizes are very close in terms of overall construct diameter, the distribution of the weight is different. The larger diameter of the 19" wheel means that the weight of the construct is further from the center of rotation than it is in the smaller wheel. Metal weighs more than rubber, and even if you assume that the rubber weighs the same in either construct, that weight is slightly further from the center of rotation. As a result of this change in weight distribution, the gyroscopic stabilization forces in the larger construct are higher. This means that the larger construct requires more force to achieve comparable results in braking and steering compared to the smaller construct. It also means that greater forces are transmitted to the suspension components of the vehicle through the increased torque of the wheel/tire construct. These forces increase dramatically in extreme situations, such as track use.
For this reason, Porsche modified the suspension of the 997 vehicles to compared to the 996 vehicles. The 997 was offered from the factory with 19" wheels, and Porsche knew that some people would track their vehicle. The vehicle was designed to withstand the increased forces.
So... will this really matter or will you be able to feel the difference? I have no idea. Many people track these cars with 19" wheels and never report a problem.
Another thing to think about if track use is important to you: consider the wheels and tires used on modern race cars. If you look at a Formula 1 car, you'll see that the wheel diameters are quite small compared to street cars. These cars are designed for optimum performance on the track, and if larger diameter wheels performed better, they would be used by the F1 teams.
Perhaps you should conisder a set of track wheels and keep your street wheels if you really like them.
05-12-2014, 02:24 PM
#9
I have read many posts indicating that the 996 was set up with 18" wheels therefore it handles better. But very little real data or first-hand opinions.
The sidewall between the 18" wheels and 19" is either the same (3.5") or within 10% depending on the tire choices.
Tirerack indicates that the weights of the tires on the same for 18" and 19" at least for the 295/35ZR18 and 295/35ZR19 Michelin Pilot Sport tires (28 pounds).
Stock 19" rims appear to be slightly heaver than 18" but the much bigger factor is the design of the wheels. A good summary is here: http://www.944racing.de/wheelweights.php
The 18x11 Sport Techno rims weigh 11.9KG (26 pounds) which is heavier than most of the afterweight 19" rims although it is really hard to find the weight of various rims. I was looking at Victor, OZ. For example OZ Ultraleggera HLT in 19x11 weigh 24 pounds.
So the sidewalls are almost the same, the weights of the tires are the same, and the weights of aftermarket 19"s are usually lower than stock 18"s.
So has anyone tried 18 vs 19" rims on the same car and could tell the difference in handling both as a DD and track?
The sidewall between the 18" wheels and 19" is either the same (3.5") or within 10% depending on the tire choices.
Tirerack indicates that the weights of the tires on the same for 18" and 19" at least for the 295/35ZR18 and 295/35ZR19 Michelin Pilot Sport tires (28 pounds).
Stock 19" rims appear to be slightly heaver than 18" but the much bigger factor is the design of the wheels. A good summary is here: http://www.944racing.de/wheelweights.php
The 18x11 Sport Techno rims weigh 11.9KG (26 pounds) which is heavier than most of the afterweight 19" rims although it is really hard to find the weight of various rims. I was looking at Victor, OZ. For example OZ Ultraleggera HLT in 19x11 weigh 24 pounds.
So the sidewalls are almost the same, the weights of the tires are the same, and the weights of aftermarket 19"s are usually lower than stock 18"s.
So has anyone tried 18 vs 19" rims on the same car and could tell the difference in handling both as a DD and track?
A few years ago, I had a 2002 Audi S4tt that had most of the mods available at the time and was making ~450-500hp depending on who's dyno you believed.
I had two sets of summer wheels a set of 19" forged Audi R8 wheels (fronts all around) and a set of BBS CH in 18". Despite the 19's being lighter(!) the car worked far better on 18's in every category- acceleration, braking, grip, feel, etc. It just didn't look as cool, because the spindly design of the 19's showed off the huge, six piston brembos...
Part of it isn't down to absolute weight, but the distribution of the MASS. If more of the mass is out toward the rim, as is the case with larger wheels, it takes more energy to accelerate, decelerate, and turn (larger gyroscope.) the extra energy that goes into these actions masks responsiveness and feel. Google the term "polar moment of inertia" and see what you come up with...
In addition, if your sidewall heights on 19's and 18's are the same, you've also made your gearing taller, which will further reduce acceleration and braking performance.
HTH!
05-12-2014, 03:15 PM
#10
Pro
Thread Starter
Thanks Coffeehead and Dennis.
The real-world feedback was what I was looking for.
I'm aware of the physics behind rotational inertia and the polar moment of inertia but determining the real and noticeable impact on a car is pretty difficult to determine :-)
My uneducated guess was that that the differences in polar moment wouldn't have a noticeable impact are relatively low speeds (ie street speeds) since the weight of the wheels is relatively low and the rotational speed isn't that high...but might be noticeable at the track.
It sounds like that might not be true.
I wasn't able to find the weight of my Antera 343 rims but I just weighed them today. The total weight of my front 19" rims plus 235/35ZR19 Michelin PSS tires was almost 49 pounds. Subtracting off the tires resulted in an estimate of 26 pounds for the rim. Pretty heavy.
The 18" Sport Techno rims are apparently 20.7 pounds and the tires for the front would be ~2 pounds less.
So that means a savings of almost 7 pounds or ~15% going from 19 to 18 on a smaller diameter.
It sounds like that might be noticeable on the street in handling. Obviously lower gearing for acceleration and lower rotational inertia which is nice.
If an 18" wheel offers better handling though, then why are the sports cars now shipping (including Porsche) with 20" and larger rims? I assume it is just that bling outsells speed.
The real-world feedback was what I was looking for.
I'm aware of the physics behind rotational inertia and the polar moment of inertia but determining the real and noticeable impact on a car is pretty difficult to determine :-)
My uneducated guess was that that the differences in polar moment wouldn't have a noticeable impact are relatively low speeds (ie street speeds) since the weight of the wheels is relatively low and the rotational speed isn't that high...but might be noticeable at the track.
It sounds like that might not be true.
I wasn't able to find the weight of my Antera 343 rims but I just weighed them today. The total weight of my front 19" rims plus 235/35ZR19 Michelin PSS tires was almost 49 pounds. Subtracting off the tires resulted in an estimate of 26 pounds for the rim. Pretty heavy.
The 18" Sport Techno rims are apparently 20.7 pounds and the tires for the front would be ~2 pounds less.
So that means a savings of almost 7 pounds or ~15% going from 19 to 18 on a smaller diameter.
It sounds like that might be noticeable on the street in handling. Obviously lower gearing for acceleration and lower rotational inertia which is nice.
If an 18" wheel offers better handling though, then why are the sports cars now shipping (including Porsche) with 20" and larger rims? I assume it is just that bling outsells speed.
05-12-2014, 03:27 PM
#12
Rocky Mountain High
Rennlist Member
Rennlist Member
I think you're right about the bling. The gearing was changed in the 997 vs. the 996 to accomodate the differences in performace with the larger wheels. I suspect the 991 is the same way.
The 19" and 20" wheels do look damn good!
The 19" and 20" wheels do look damn good!
05-27-2014, 11:46 PM
#14
Pro
Thread Starter
Just an update for anyone reading. I decided to bit the bullet and try downsizing. Although I'm still not 100% sure which solution I'll keep.
I found a set of Sport Techno rims with Hankook v12 evo's. The seller had indicated that the rims were near perfect and the tires were only used for one season. As it turned out 2 of the rims had some significant curb rash and the rear tires were at the wear bars. I ended up buying anyway at a much reduced price mostly since I didn't want to waste the 3 hours I had committed :-(
I definitely prefer the look of the 19" antera rims. The brakes are much more obvious and the car looks a bit more modern IMO. The 18" sport techno's are nice, but they are missing the big lip and bright finish. I might try refinishing them with a shiny or silver-flaked powder coat to make them pop a little more. I do have spacers for the front which will help since they are pretty sunken-in otherwise.
The ride is slightly softer and more bearable on the 18"s. The change is mostly with smaller bumps and I can think I can take bumps with a little less caution than before. The change is pretty subtle though I'm going to re-install my 19"s this weekend just to be absolutely sure. I suspect some of that is due to the softer sidewall of the Hankooks compared to the Michelin's but it could also be due to a little more sidewall up-front. I'm happy with the improvement and will probably keep the 18"s for that reason alone.
The front also feels a bit easier to steer due to the smaller tires. The back-end definitely slides out more but I blame that one on worn tires. I'm pretty impressed with the Hankooks otherwise.
I haven't noticed any change in acceleration or braking on the street as expected but I do have a track day booked in a few weeks that might highlight the differences.
My speedometer now reads too low which is annoying after having it almost perfect.
Note that the first is in bright sunlight and the second picture is at dusk so the comparison isn't quite fair. But as expected I think the main conclusion is that 19" is for 'bling' and 18" is for 'go'.
I found a set of Sport Techno rims with Hankook v12 evo's. The seller had indicated that the rims were near perfect and the tires were only used for one season. As it turned out 2 of the rims had some significant curb rash and the rear tires were at the wear bars. I ended up buying anyway at a much reduced price mostly since I didn't want to waste the 3 hours I had committed :-(
I definitely prefer the look of the 19" antera rims. The brakes are much more obvious and the car looks a bit more modern IMO. The 18" sport techno's are nice, but they are missing the big lip and bright finish. I might try refinishing them with a shiny or silver-flaked powder coat to make them pop a little more. I do have spacers for the front which will help since they are pretty sunken-in otherwise.
The ride is slightly softer and more bearable on the 18"s. The change is mostly with smaller bumps and I can think I can take bumps with a little less caution than before. The change is pretty subtle though I'm going to re-install my 19"s this weekend just to be absolutely sure. I suspect some of that is due to the softer sidewall of the Hankooks compared to the Michelin's but it could also be due to a little more sidewall up-front. I'm happy with the improvement and will probably keep the 18"s for that reason alone.
The front also feels a bit easier to steer due to the smaller tires. The back-end definitely slides out more but I blame that one on worn tires. I'm pretty impressed with the Hankooks otherwise.
I haven't noticed any change in acceleration or braking on the street as expected but I do have a track day booked in a few weeks that might highlight the differences.
My speedometer now reads too low which is annoying after having it almost perfect.
Note that the first is in bright sunlight and the second picture is at dusk so the comparison isn't quite fair. But as expected I think the main conclusion is that 19" is for 'bling' and 18" is for 'go'.
