Looking for power loss RESULTS from 20" wheels
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Joined: Jan 2009
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From: Sydney
I am just worried about turning my quick z into a slug because I wanted 20 inch rollers instead of 19's. I am not going smaller than 19, so I guess you are right in the fact that the difference from 19 to 20 is like the popcharger comparison. I do worry about the bending issue, I live in CT, the roads can be bad sometimes especially after the winter with potholes, and I have bent a rim before.
Going from 18" stock to some chromed heavy 20" -will- make a considerable difference, especially (and I assume you will if you're after look) if you also go for wide.
Weight, weight distribution and design, materials and their properties all contribute to change the behaviour of the car, sometimes considerably.
You're likely to lose a good chunk of change on 0-60 and some on 60-100, but what's worse is that braking will also change, not drastically but noticeably, especially at high speed.
It won't become a focus diesel with 300+ hp and efficient transmission, but definitely forget the pleasure of seeing a boxster in the rear-view mirror that you'd enjoy even at stock.
Performance aside, you also have to consider the tangent vector of a good braking without tyre compression and so far from the hub; it -will- generate an asston more torque at the hub, even more-so with wider wheels, and you're more likely to feel the ABS kicking in early and add a fair few feet in an emergency brake.
Vibrations, uneven load, side traction and basically any force measured by it momentum (force multiplied by distance from the constraint) will also feel way worse.
I had 19's on my last car and I have learned to drive carefully and have been issue free for awhile now... But when you think about how much difference from the 19 inch tire with a 35 series sidewall vs a 20 inch with a 30 series sidewall... it really doesn't make much difference, I believe that what matters more is the fact that it is larger and weaker...
You aren't going from 35 to 30 and hence lowering the profile, you are going from 35% to 30%, so without knowing what width of tyre was on the previous tyre, this doesn't make a lot of sense
If your old car had 205/35 and you're moving to 285/30 your sidewall will still be considerably taller, not shorter. In those regards, if your previous car wasn't in the same class of the Z, you're likely to still come out on top.
My other concern is that I am dropped on coilovers, and I will have less room to lower the car won't I if I go with a 20 inch wheel...
If you go 20 you have to reduce the wall compared to a 19, the overall tyre height remains the same.
Shoulder shape, width and offsets are the only concerns when slamming. 17 or 20 inches wheel makes no difference to the distance between fender and asphalt.
You're free to do whatever you want with your car, and if it's just a daily driver and you never push it on the road (I'd hope not) or on the track (your loss
) then it will still be a better and safer car than your average souped up ricer even with 20" wheels. Ultimately though the wider and taller you go, the more issues you get.The ROI goes negative at 16, 17 or 18 for the Z, depending on application and use, anything after that you're sacrificing performance, handling and safety for looks in any and every situation.
How much you care or notice depends from what kind of driver you are and how you use your car. Anybody saying differently, I'm sorry to say, is ignoring some pretty basic lessons in physics, mechanics and driving
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From: Windsor/Storrs, CT
Thanks everyone for all the great tips and info, I hope this thread helps others with similar questions as well, I beleive I am going to go with the 19's rather then the 20's, for the added durability and less potential performance loss. The 19's will look plenty big while I'm slammed
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Joined: Jan 2009
Posts: 48
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From: Sydney
19" will look good.
Another thing that does a lot for looks that people overlook, blinded by diameter, is the design of the rim combined with the shape of the tyre's shoulder.
Low profile tyres on gigantic rim (that force you on certain angles and proportions if you don't stretch) often look good because of the straight wall and cut corner shoulder section that come with the territory.
If you pick a tyre you like aesthetically, with an aggressive section, and sit it on a wheel of the right width, you'll probably get what you're really after even with 19".
IE: I went from stock to 18" bronze xd9 and have fk452 (didn't do it for looks, mostly I wanted wider wheels of comparable weight and got cheap enough tyres to learn to handle the car on track for a while before I start working on it), and it almost looks like a downgrade with the rounded shoulder and the diminutive design of the wheel, even if the walls are perfectly vertical.
When I had a bit of a test drive on some yoko advan of very different cut the shoes were looking a lot better.
Mind, I didn't care much for how big they looked, they drive well, were reasonably priced, and I tend to be on the other end of rice on the conservative scale in looks.
It takes both things for looks imo, wheel and tyre, tallest wheel you can get with the tyre practically painted on it just constrains one of the two factors
Another thing that does a lot for looks that people overlook, blinded by diameter, is the design of the rim combined with the shape of the tyre's shoulder.
Low profile tyres on gigantic rim (that force you on certain angles and proportions if you don't stretch) often look good because of the straight wall and cut corner shoulder section that come with the territory.
If you pick a tyre you like aesthetically, with an aggressive section, and sit it on a wheel of the right width, you'll probably get what you're really after even with 19".
IE: I went from stock to 18" bronze xd9 and have fk452 (didn't do it for looks, mostly I wanted wider wheels of comparable weight and got cheap enough tyres to learn to handle the car on track for a while before I start working on it), and it almost looks like a downgrade with the rounded shoulder and the diminutive design of the wheel, even if the walls are perfectly vertical.
When I had a bit of a test drive on some yoko advan of very different cut the shoes were looking a lot better.
Mind, I didn't care much for how big they looked, they drive well, were reasonably priced, and I tend to be on the other end of rice on the conservative scale in looks.
It takes both things for looks imo, wheel and tyre, tallest wheel you can get with the tyre practically painted on it just constrains one of the two factors
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Joined: Nov 2008
Posts: 237
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From: Sydney
Going from cast 18" stock to 19" forged might be like the popcharger comparison.
Going from 18" stock to some chromed heavy 20" -will- make a considerable difference, especially (and I assume you will if you're after look) if you also go for wide.
Weight, weight distribution and design, materials and their properties all contribute to change the behaviour of the car, sometimes considerably.
You're likely to lose a good chunk of change on 0-60 and some on 60-100, but what's worse is that braking will also change, not drastically but noticeably, especially at high speed.
It won't become a focus diesel with 300+ hp and efficient transmission, but definitely forget the pleasure of seeing a boxster in the rear-view mirror that you'd enjoy even at stock.
Performance aside, you also have to consider the tangent vector of a good braking without tyre compression and so far from the hub; it -will- generate an asston more torque at the hub, even more-so with wider wheels, and you're more likely to feel the ABS kicking in early and add a fair few feet in an emergency brake.
Vibrations, uneven load, side traction and basically any force measured by it momentum (force multiplied by distance from the constraint) will also feel way worse.
The sidewall number is a percentage, not a length.
You aren't going from 35 to 30 and hence lowering the profile, you are going from 35% to 30%, so without knowing what width of tyre was on the previous tyre, this doesn't make a lot of sense
If your old car had 205/35 and you're moving to 285/30 your sidewall will still be considerably taller, not shorter. In those regards, if your previous car wasn't in the same class of the Z, you're likely to still come out on top.
The overall diameter is unaffected by wheel size.
If you go 20 you have to reduce the wall compared to a 19, the overall tyre height remains the same.
Shoulder shape, width and offsets are the only concerns when slamming. 17 or 20 inches wheel makes no difference to the distance between fender and asphalt.
You're free to do whatever you want with your car, and if it's just a daily driver and you never push it on the road (I'd hope not) or on the track (your loss ) then it will still be a better and safer car than your average souped up ricer even with 20" wheels. Ultimately though the wider and taller you go, the more issues you get.
The ROI goes negative at 16, 17 or 18 for the Z, depending on application and use, anything after that you're sacrificing performance, handling and safety for looks in any and every situation.
How much you care or notice depends from what kind of driver you are and how you use your car. Anybody saying differently, I'm sorry to say, is ignoring some pretty basic lessons in physics, mechanics and driving
Going from 18" stock to some chromed heavy 20" -will- make a considerable difference, especially (and I assume you will if you're after look) if you also go for wide.
Weight, weight distribution and design, materials and their properties all contribute to change the behaviour of the car, sometimes considerably.
You're likely to lose a good chunk of change on 0-60 and some on 60-100, but what's worse is that braking will also change, not drastically but noticeably, especially at high speed.
It won't become a focus diesel with 300+ hp and efficient transmission, but definitely forget the pleasure of seeing a boxster in the rear-view mirror that you'd enjoy even at stock.
Performance aside, you also have to consider the tangent vector of a good braking without tyre compression and so far from the hub; it -will- generate an asston more torque at the hub, even more-so with wider wheels, and you're more likely to feel the ABS kicking in early and add a fair few feet in an emergency brake.
Vibrations, uneven load, side traction and basically any force measured by it momentum (force multiplied by distance from the constraint) will also feel way worse.
The sidewall number is a percentage, not a length.
You aren't going from 35 to 30 and hence lowering the profile, you are going from 35% to 30%, so without knowing what width of tyre was on the previous tyre, this doesn't make a lot of sense
If your old car had 205/35 and you're moving to 285/30 your sidewall will still be considerably taller, not shorter. In those regards, if your previous car wasn't in the same class of the Z, you're likely to still come out on top.
The overall diameter is unaffected by wheel size.
If you go 20 you have to reduce the wall compared to a 19, the overall tyre height remains the same.
Shoulder shape, width and offsets are the only concerns when slamming. 17 or 20 inches wheel makes no difference to the distance between fender and asphalt.
You're free to do whatever you want with your car, and if it's just a daily driver and you never push it on the road (I'd hope not) or on the track (your loss
) then it will still be a better and safer car than your average souped up ricer even with 20" wheels. Ultimately though the wider and taller you go, the more issues you get.The ROI goes negative at 16, 17 or 18 for the Z, depending on application and use, anything after that you're sacrificing performance, handling and safety for looks in any and every situation.
How much you care or notice depends from what kind of driver you are and how you use your car. Anybody saying differently, I'm sorry to say, is ignoring some pretty basic lessons in physics, mechanics and driving
Wider tires help grip and handling, while wider wheels are required to mount the larger tires. The wider wheels/tires can decrease performance in the respect that increased wheel/tire weight and inertia require more power to spin up to speed, which would result in the car feeling 'sluggish' while accelerating. Meanwhile you want to have plenty of rubber on the road while maneuvering any kinds of twists and turns so that you can transmit the power from the tire to the road, so in that case having wider tires is key. It's really all about striking a balance between maximizing tire contact patch while minimizing wheel+tire weight and inertia. I believe in mathematics they call this 'optimization'.
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Joined: Nov 2008
Posts: 237
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From: Sydney
Wider tires help grip and handling, while wider wheels are required to mount the larger tires. The wider wheels/tires can decrease performance in the respect that increased wheel/tire weight and inertia require more power to spin up to speed, which would result in the car feeling 'sluggish' while accelerating. Meanwhile you want to have plenty of rubber on the road while maneuvering any kinds of twists and turns so that you can transmit the power from the tire to the road, so in that case having wider tires is key. It's really all about striking a balance between maximizing tire contact patch while minimizing wheel+tire weight and inertia. I believe in mathematics they call this 'optimization'.
Or is that a massively complicated question to answer?.. I am thinking of getting some forged 19's for looks sake, and also want to increase the width... but not sure how wide to go without sacrificing performance...
nice... so on a Z, what would be the optimal width for wheels & associated tire width without sacrificing performance?
Or is that a massively complicated question to answer?.. I am thinking of getting some forged 19's for looks sake, and also want to increase the width... but not sure how wide to go without sacrificing performance...
Or is that a massively complicated question to answer?.. I am thinking of getting some forged 19's for looks sake, and also want to increase the width... but not sure how wide to go without sacrificing performance...
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Joined: Apr 2020
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From: Puerto Rico (PR)
Chrome z
I used the search but couldn't find the specific info I am looking for.
I am trying to gauge the amount of power lost from having 20 inch wheels, more specifically versus 19 inch wheels. I know that weight has everything to do with it so for the purposes here just consider average range weights, no $6k ultra light weight ones. Anyone have a dyno or actual quantifiable numbers for the loss of power?
I do NOT want to start another endless debate about wheel sizes I am just looking for this specific information, and I know both sizes are more visual oriented rather than performance, I am just looking for some results and to get an idea about the expected power loss going from 19 to 20 inch wheels from those of you who have ACTUALLY driven/ridden in both. I basically need to make a purchase decision and I need to hear others' experiences, not just what they've heard, as in I am looking for either A) it really makes no difference its only 10-15 lbs total all around for 20's over 19's, its nothing or B) it makes a hell of a difference, it feels a lot slower don't bother if you want your car to still pull
That's all, Thanks in advance
I am trying to gauge the amount of power lost from having 20 inch wheels, more specifically versus 19 inch wheels. I know that weight has everything to do with it so for the purposes here just consider average range weights, no $6k ultra light weight ones. Anyone have a dyno or actual quantifiable numbers for the loss of power?
I do NOT want to start another endless debate about wheel sizes I am just looking for this specific information, and I know both sizes are more visual oriented rather than performance, I am just looking for some results and to get an idea about the expected power loss going from 19 to 20 inch wheels from those of you who have ACTUALLY driven/ridden in both. I basically need to make a purchase decision and I need to hear others' experiences, not just what they've heard, as in I am looking for either A) it really makes no difference its only 10-15 lbs total all around for 20's over 19's, its nothing or B) it makes a hell of a difference, it feels a lot slower don't bother if you want your car to still pull
That's all, Thanks in advance
New Member
Joined: Oct 2003
Posts: 334
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From: San Bruno, Ca
Trade off...
I just got 19" volks. I had 20" Axis mod 7 for a long time. I noticed a light drop in acceleration when I went from 17" to 20"s. The car was fast but not that quick off the line. The 20"s looked good though so I kept it on for years. After recenyly getting the 19"s, I immediately felt the performance gain again.....
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Joined: Apr 2020
Posts: 6
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From: Puerto Rico (PR)