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Car feels slower or not as aggressive when accelerating

5ohaejun

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I recently changed my wheel set up, went from 265/35/20 square to 275/35/20 fronts and 315/35/20 rears. I don’t know if it’s placebo but the car feels slower or more sluggish in terms of the gearing. It kind of makes sense why it could be slower, wider tires whatever, but does anyone know the any specific reason or knowledgeable in this. I don’t mind at all right now I’m just getting my suspension and wheels done before adding power but just good to know.
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I recently changed my wheel set up, went from 265/35/20 square to 275/35/20 fronts and 315/35/20 rears. I don’t know if it’s placebo but the car feels slower or more sluggish in terms of the gearing. It kind of makes sense why it could be slower, wider tires whatever, but does anyone know the any specific reason or knowledgeable in this. I don’t mind at all right now I’m just getting my suspension and wheels done before adding power but just good to know.
Yeah, you increased your rear tire height by almost 1.5” or over 5%. This effectively raised you rear gear ratio which reduces the the rate of acelleration making the car feel slower from the jump. Whether or not you can actually feel this amount of difference is debateable or it could be a placebo effect but the fact is the car will have less off the line acceleration because of the taller rear tire.
The good news is you could get better fuel economy ifyou do much highway driving. Whoot!
 

HKusp

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Also you need to consider if your new wheel and tire combo is heavier than the previous set-up. Unsprung weight increases can make the car feel sluggish and less nimble.
 
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5ohaejun

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Yeah, you increased your rear tire height by almost 1.5” or over 5%. This effectively raised you rear gear ratio which reduces the the rate of acelleration making the car feel slower from the jump. Whether or not you can actually feel this amount of difference is debateable or it could be a placebo effect but the fact is the car will have less off the line acceleration because of the taller rear tire.
The good news is you could get better fuel economy ifyou do much highway driving. Whoot!
sorry, I don’t understand this part. How is it higher? And is there a way increase the rate of acceleration somehow?
 

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5ohaejun

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Also you need to consider if your new wheel and tire combo is heavier than the previous set-up. Unsprung weight increases can make the car feel sluggish and less nimble.
The rims are definitely lighter, but the tires are probably heavier given how much wider they are
 

Dinokill3.7

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sorry, I don’t understand this part. How is it higher? And is there a way increase the rate of acceleration somehow?
The taller the tire is, the slower it takes to do a full rotation so your RPM will climb slower than having a smaller tire.

On the other hand, taller tires cover more distance when doing a full rotation so your top speed will be higher with a taller tire.

Hope this helps.
 

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Using two tire sites to search for factory-sized offerings, I rolled back to what I think would be an original stock setup, then moved to your new tires.

235/50/18 - 27.25" (Possible original size)

255/40/19 - 27.03" (Possible original size)

275/35/20 - 27.58" (New Front, +1.2 to 2.0%)

315/35/20 - 28.68" (New Rear, +5.2 to 6.1%)

A general rule of thumb is not to stray far from +/- 3%.

As mentioned earlier, you've effectively changed the gear ratio. Think of a bike sprocket. As you move to a physically taller cog, you pedal faster and go slower.

The car's Powertrain Control Module and Body Control Modules are programmed with certain ranges and limits. While not damaging anything, logical parameters (shift points, ABS, speedo, etc.) might need some adjustment to compensate.
 
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GrayMater22

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I recently changed my wheel set up, went from 265/35/20 square to 275/35/20 fronts and 315/35/20 rears. I don’t know if it’s placebo but the car feels slower or more sluggish in terms of the gearing. It kind of makes sense why it could be slower, wider tires whatever, but does anyone know the any specific reason or knowledgeable in this. I don’t mind at all right now I’m just getting my suspension and wheels done before adding power but just good to know.
Several others have mentioned tire height and weight which are both proven factors, but you have also increased your rolling resistance with much wider tires in front and rear. Due to the large amount you have increased your rear tire height, I would highly recommend to change your tire height in your ecu if you have a tuner, your speedo will be off quite a bit.
 

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I recently changed my wheel set up, went from 265/35/20 square to 275/35/20 fronts and 315/35/20 rears. I don’t know if it’s placebo but the car feels slower or more sluggish in terms of the gearing. It kind of makes sense why it could be slower, wider tires whatever, but does anyone know the any specific reason or knowledgeable in this. I don’t mind at all right now I’m just getting my suspension and wheels done before adding power but just good to know.
Given that the OP was unaware that tire height is a factor in the effective final drive ratio I think the placebo effect can be ruled out.
 

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The rims are definitely lighter, but the tires are probably heavier given how much wider they are
How much lighter? You went from a 265 tire to a 315 tire, I am assuming you added at least an inch to your rim. Probably more to make a 315 fit properly.

Unless you went forged, I am betting you dropped way less than you think. And that additional mass is further from the axle, meaning there is more weight out far from the center of rotation, which means it will be harder to accelerate the while.

The short answer is physics.
 
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5ohaejun

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How much lighter? You went from a 265 tire to a 315 tire, I am assuming you added at least an inch to your rim. Probably more to make a 315 fit properly.

Unless you went forged, I am betting you dropped way less than you think. And that additional mass is further from the axle, meaning there is more weight out far from the center of rotation, which means it will be harder to accelerate the while.

The short answer is physics.
If I remember correctly Project6Grs are flow formed. I believe the 20x11s on the rear are around 26 lbs give or take. Even holding my stock rears were noticeably heavier versus holding the Project6Grs.
 
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5ohaejun

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Using two tire sites to search for factory-sized offerings, I rolled back to what I think would be an original stock setup, then moved to your new tires.

235/50/18 - 27.25" (Possible original size)

255/40/19 - 27.03" (Possible original size)

275/35/20 - 27.58" (New Front, +1.2 to 2.0%)

315/35/20 - 28.68" (New Rear, +5.2 to 6.1%)

A general rule of thumb is not to stray far from +/- 3%.

As mentioned earlier, you've effectively changed the gear ratio. Think of a bike sprocket. As you move to a physically taller cog, you pedal faster and go slower.

The car's Powertrain Control Module and Body Control Modules are programmed with certain ranges and limits. While not damaging anything, logical parameters (shift points, ABS, speedo, etc.) might need some adjustment to compensate.
I see, thank you
 

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If I remember correctly Project6Grs are flow formed. I believe the 20x11s on the rear are around 26 lbs give or take. Even holding my stock rears were noticeably heavier versus holding the Project6Grs.
The wheel MIGHT be 6 lbs less. But without weighing them, it's impossible to know. If you didn't weigh rim and tire vs rim and tire, you wont know. And again, I go back to, more mass is concentrated at the edge of the circle, not the center, so it takes way more work to get a wheel rolling.
 

Andy13186

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Probably could just be mainly because you have better traction. Unless you were dead hooking on the old tires.
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