LexusFirst

I am looking at the spec on the IS F sport spec. I find the the size of the front and rear tire is different.
The rear is P255/35R18
The front is P225/40R18

I am going to buy another set of rim and winter tire.
Do you guy know if I should get the same sizes as the factory one or either one of the sizes for all 4 wheels and tires?
Should I go for the P255/35R18 or the P225/40R18 if I buy all 4 wheel and tires at the same size.

Do you guys know the the offsets of the factory wheels?
Thank you

AdvanSLF

for snow, the best setup is a square setup, meaning all four rims and tires are the same width. reason being is that the rear tires will run on the same tread laid down by the front tires thus providing more contact and grip. additionally, you can rotate them for the most part anyway you want. if you get staggered wheels, you can only rotate them side to side. if you are going square you need to get 225 around. i don't think the front wheel well will clear anything beyond that. offsets of factory wheels are 18x8 +45 for fronts and 18x8.5 +50 for rears, if i remember correctly.

LexusFirst

You explanation is amazing. Thank you
I just want to confirm the front wheel offset. I have been searching for a long time and no luck for me.

BTW, since the stock wheel size is different, I don't think the tire can be rotated front to back.
Is the side to side rotate necessary for the stock all season tires? Are they directional tires?

Jeremy1976

I am thinking about a winter tire/wheel setup as well and was wondering this same question. I am glad we do not have to go staggered for winter! Thanks for the input!

AdvanSLF

Front F Sport wheels are 18x8, +45 et. You are correct, since they are different widths, you can't move them front to back and vice versa. You can only move them side to side IF and only IF you have asymmetrical or symmetrical tires--directional tires should not be swapped hence they are directional.
You probably don't want to know this as its more information than you need to, but technically you can swap directional tires from side to side, however, this includes dismounting and remounting your tires on the other rim of the other side of the car, which is a pain and won't be good for the longevity of your tire because every dismount and remount takes life away from the tire's wall where it clings to the rim to support holding in air. if you dismount too many times, it won't hold air any longer and would be useless. thus, doing this is useless.
also if you have driven quite a bit already on your tires, say more than 10k miles on your original set of tires, don't rotate at this point, as the car would pull and not go straight once you rotate them. the tires have gotten used to the pattern of where they are, so it wouldn't be effective. i'm in the same boat. i thought my bridgestone turanza ER33 were directional but i wasn't sure and was too lazy to look it up. i find out 20k miles later they are symmetrical which i could have rotated. i'm probably just going to let it sit where it is and once i need to replace tires, i'll then buy new ones and rotate them every 5k miles.
if you're looking for winter tires, i hear good things of the bridgestone blizzaks, for all seaons, go with the continental dws or michelin as3

here's some info from tire rack which is a good source to learn from.
http://www.tirerack.com/tires/survey...sp?type=W&VT=C

LexusFirst

I don't want to give up tire lifetime for performance.
I am thinking between Michelin X-Ice Xi3 and WS80. I heard they last long with ok performance.
From my research, WS80 is better on ice, but xi3 is a little better on dry road.

One more question, can 17" rim fit on F sport car? Would it be too small for the F Sport brake ?
I think 17" rim can save a little weight. A thicker tire might reduce road noise as well. I guess it only hurt the look by a little.
I am trying to figure out the proper size of 17" rim and tire.
This is my first time to do this.
If I use the 225 40R18 as a reference
225mm = 8.85827inches
OD = 8.85827 x 0.40 + 18 = 21.543308inches

To fill in the blank, a 17" rim with 225 would be 50R ~~~~(21.54-17)/8.85
Would 225 50R17 the best tire that would not ruin the odometer?

AndyL

I have 17" rims for winter setup for my IS350 AWD and the size is 225/45R17 for all 4.

Actually it is the default size for stock IS in some countries such as Japan for IS250/350. And it hurts the look definitely but it works well in snow and ice.

LexusFirst

I check the 250 spec. Yes, they use that size.
I think there is 0.5 inches difference on the OD compared to the OEM tire
Does it affect the odometer reading?

I think 17" looks fine as I see it looks great on 250.

AndyL

I haven't paid close attention to the variance in odometer reading but my logic is if 225/45R17 is standard default configuration for IS250 (& IS350, in some countries, say Japan specifically), the car manufacturer , i.e., Lexus should have taken care of any odometer issue. So no need to worry about it.

LexusFirst

What is the offset on your 17" wheel?

Does anyone know the offset on the OEM 17" wheel?
I searched some 17 wheels, they are only available with 35mm offset. I am not sure if it would affect the handling of the car as the 18" OEM wheel has a 45mm offset.

donstello

http://www.wheel-size.com/size/lexus/is/2016/

225/45R17 91Y
8Jx17 ET45 width 8, diameter 17, positive offset by 45
5x114.3
M12 x 1.5 60.1

GSpearlwht

Hi guys. I'm new to the Is F sport family. I recently bought a 2017 IS 200t blue. It's an amazing machine. I wanted to know if I can add on rear tires, from 255/35/18 to 255/40/18 to match the thickness of the fronts?

Can it be done without causing any odometer warning signs ect ect?

Sonic the hedgehog

Sid03SVT

Firstly, welcome to the forum.

Secondly, to your questions:
A 255/35R18 and a 225/40R18 have the same amount of sidewall; as the second number is a percentage of the tread width (called the aspect ratio) so 35% of 255 = 40% of 225.
-first number - tread width in mm
-second number - aspect ratio (percentage of tread width as sidewall height)
-third number - is the rim size (R18 = 18")
If you switch to a 255/40R18 from a 255/35R18, yes your speedo will be off.
As to mechanical issues, only if the vehicle is AWD as the overall tire diameter needs to be the same front and rear in an AWD car (a 200t is not AWD).

Hope that helps.