Changing from 17" to 15"

[Revengeance]

Hi everyone! I'm new in this forum and seeking for help!
Forgive me for my bad grammars anyway..

My problem is, im currently using dirreza 205/40r17 works 17x8j +40 tires and wheel respectively. And im planning to change it back to 15". I just wanted to know a good size/fitment for my car in 15".

Ive seen some used tires and wheel thats for sale and the sizes are

195/55r15 6.5j +28
185/55r15 5.5j +45

Im trying to avoid that rubbing sound in hard turns and my car runs really slow on an uphill thats why i want to go back to 15". Ive tried reading the wheel and tire guide but im totally new in this kind of thing. Any advice is much appreciated! And thank you in advance.

Btw im driving a 2000 vitz (scp10) 1.0L...
KYB suspension set

[yarisugi]

Is you car lowered? If so, how much lower?

[Neurotic Hapi Snak]

Stock 15" wheels are 5.5j 45mm offset with a 185/60r15 tire. That gives a tire diameter of 23.7", slightly larger than your 205/40r17 diameter, which is 23.5". The 185/55r15 5.5j +45 will give you a diameter of 23", the same as the stock 14" 5j 45mm offset with 175/65r14 tire.

[Revengeance]

Is you car lowered? If so, how much lower?

Thank you for replying! I can't say how much it is lowered but its really low! (i will try to upload pics later)
And that is one of my reasons i want to go back to 15" and even change my bumper to a vitz rs bumper one...

Stock 15" wheels are 5.5j 45mm offset with a 185/60r15 tire. That gives a tire diameter of 23.7", slightly larger than your 205/40r17 diameter, which is 23.5". The 185/55r15 5.5j +45 will give you a diameter of 23", the same as the stock 14" 5j 45mm offset with 175/65r14 tire.

Thank you for replying! Too many numbers make my nose bleed.. Anyway, i dont get the diameter thing, if the diameter is larger or smaller what will it give to my car?

[Neurotic Hapi Snak]

A larger diameter means less revolutions per a given distance (effectively a higher gear ratio) but you run into fitment issues with larger diameters or they rub when turning or going over bumps. It's a good idea to stick close to the stock tire diameter. Also with offset, the lower the offset, the farther the tire "sticks out", too low and you will rub your fenders on bumps. Too high and the wheel might hit the suspension.

[Revengeance]

A larger diameter means less revolutions per a given distance (effectively a higher gear ratio) but you run into fitment issues with larger diameters or they rub when turning or going over bumps. It's a good idea to stick close to the stock tire diameter. Also with offset, the lower the offset, the farther the tire "sticks out", too low and you will rub your fenders on bumps. Too high and the wheel might hit the suspension.


Thank you for the very informative advice!
I have 2 preferences atm

195/55r15 6.5j +28
185/55r15 5.5j +45

What do you think is good for my car? And do i also need to adjust the suspension?

[WeeYari]

You would definitely run into rubbing issues with a +28 offset.

[IllusionX]

2000 vitz came usually came with 13" or 14". You should check your door see what is the recommended size and do your calculations from there.

I'm pretty sure you need 185/55R15 for your car. That size is generally not available in N/A, hence why we have 185/60R15 stock here.

next size you can get is 195/50R15

[tooter]

I recommend 195/60/15 tires on 15x7 wheels...

http://i17.photobucket.com/albums/b90/compost_bin/car/IMG_7521_zpsc198174f.jpg

...because they retain exactly the same wheel diameter as stock so the speedometer and odometer retain their accuracy.

Offset numbers mean the larger the number the closer to the center of the car the wheel is positioned.

For example: a +25 wheel sticks out farther from the fender than a +35 wheel.

Hope that helps. :smile:

Greg

[Revengeance]

Thank you very much for all the advices!
Still in the decision of what size im going to buy..

Anyway, what will happen if i change from 17" to 15"? What i mean is, is there a change in driving? Because 1sz-fe is not that good when it comes to power.. Im just curious if its worth changing the wheel size..

[tooter]

Hey, have a go at this tire diameter comparison calculator... :smile:

http://www.tacomaworld.com/forum/tirecalc.php?tires=245-45r17-195-60r15

For example, you are running 245/45/17's.
195/60/15's are 5.7% smaller in diameter.

Diameter inches (mm)25.68 (652.3)24.21 (615)-1.47 (-37.3) -5.7%



A 5.7% smaller wheel diameter will lower the gearing on your car and will give it more performance. Smaller wheel diameter will also give you more fender clearance. Try all sorts of other sizes and see what results you get. :smile:

Greg

[Revengeance]

Hey, have a go at this tire diameter comparison calculator... :smile:

http://www.tacomaworld.com/forum/tirecalc.php?tires=245-45r17-195-60r15

For example, you are running 245/45/17's.
195/60/15's are 5.7% smaller in diameter.

Diameter inches (mm)25.68 (652.3)24.21 (615)-1.47 (-37.3) -5.7%



A 5.7% smaller wheel diameter will lower the gearing on your car and will give it more performance. Smaller wheel diameter will also give you more fender clearance. Try all sorts of other sizes and see what results you get. :smile:

Greg



Thank you! Thats a very helpful site you gave!
Noob Question though, what does revolution per mile means?

[Neurotic Hapi Snak]

Thank you very much for all the advices!
Still in the decision of what size im going to buy..

Anyway, what will happen if i change from 17" to 15"? What i mean is, is there a change in driving? Because 1sz-fe is not that good when it comes to power.. Im just curious if its worth changing the wheel size..

A smaller wheel will decrease your rotational mass, so you will be able to accelerate quicker. Lighter wheels also tend to give better handling.

Revolutions per mile is the number of complete turns of the tire when traveling one mile (1.6 Km). A tire with a larger diameter will make fewer turns when traveling one mile, a tire with a smaller diameter will turn more per mile.

[Revengeance]

A smaller wheel will decrease your rotational mass, so you will be able to accelerate quicker. Lighter wheels also tend to give better handling.

Revolutions per mile is the number of complete turns of the tire when traveling one mile (1.6 Km). A tire with a larger diameter will make fewer turns when traveling one mile, a tire with a smaller diameter will turn more per mile.

Thanks guys! Im gonna go with 185/55r15 5.5j +45 (the stock vitz rs aluminium wheels).. Ive learned a lot! I really appreciate all of the advice!