Solman

I purchased the 10-spoke chrome wheels from a fellow CL member, that came off an IS350. They are oem from sewell and are 18 x 8 +45 (front) and
18 x 8 1/2 +50 (back). They have no tires on them. What size would be best on them. I currently have 20's on it and am disappointed in the ride and differences in hot and cold temps. I would like to put pilots on them but not sure what size. I did read the fitment thread, which only confused my simple mind. Anyone, please?

John

maisinh

I am using 225/45-18 front and 255/40-18 rear. I am thinking the next set will be 235/45-18 all around so I can rotate them although I am not so sure about the rotation since the wheels are differrent (18x8 and 18sx8.5) Hope someone give me some advices

talwang

iTrader: (4)

Just go with 245/40 all around and call it a day.
You can still do side to side rotation, but dismounting and mounting tires may be required depending on the thread patterns.

The one half inch increased in width is canceled out by the +5 increased in offset, so you can't spot the difference visually.
It will look 100% like your sc430 stock setup fitment wise.

BNR34

iTrader: (1)

Yeah but the rear sidewall would appear smaller due to the extra stretch on the sidewall from the 1/2 inch wider wheels, it would look weird IMO.

If it is my set up, I would do the stock 245/40 on the front since that rim is the same as stock on the SC430, and do 255/40 or even 265/40 on the rear for that beefy muscle car look But then you lose the ability to rotate the tire.

talwang

iTrader: (4)

My friend has the same setup on his Acura.
Man, I wouldn't call 245 on 8.5" stretched because I can't really tell the difference in the sidewall height.

255/40 has slightly larger diameter than 245/40 and would cause a little off (1.25%) on the speedometer.
265/40 is even worse, and I believe the minimum rim width recommended for 265 is 9".

Solman

Went to "Americas Tires" and ordered Pilot Sport A/S Plus. They recommended 245/40 on the fronts and 275/35 on the rear. They did this by looking up the stock SC data and comparing it with the IS350 which is what these rims are an upgrade for. They said it will appear to be the same size tire all around. Hopefully, IF there is a problem, they will stand behind their own advice.

The main reason for this switch is a blow out that I had in summer (you might remember my old post). I had to get flat-bedded 100 miles (TG for AAA) and had $2K worth of body work on my rear quarter. The body shop sent out the wheel to have it "fixed". I didn't realize it had a problem.

Continued shaking after getting it back- Had the wheels balanced and alighnment twice since then. Lexus now tells me the front rims are both bent. The tire shop is going to verify whether that is the case or not. My old ride was really great for 20" wheels.

Now I just want my ride improved. I bought the 18's from a fellow CL member. They came off an 07 IS350 and were upgraded from Sewell. They are the 10 spoke chrome. Hopefully, this will take care of it-I will know by Tuesday.

John

talwang

iTrader: (4)

245/40 and 275/35 will have nearly the same diameter.

The problem is the rim width. I think 275 is really PUSHING it on an 8.5" rim.

Maybe Pilot Sport is different, but 275 on 8.5" will more likely looks like this.

SChema

iTrader: (2)

275's are way too big of a tire for an 8.5 inch wheel. I ran 275's on a 9.5 inch wheel and that still had a slight mushrooming effect. I suggest running a 255 max on a 8.5.

maisinh

,

Thanks Talwang. Now I know what PUSHING means. I did not know PUSH, STRETCH, FLUSH...until now. You always are my hero. Now just clear my mind one last time. With 8" and 8.5" wheels and 245/40 all around can i rotate (rear to front)?? If not, PLEASE explain why.
Thanks.

talwang

iTrader: (4)

Since is350 wheels are a staggered setup, people normally don't put the wider wheels in the front.
You probably could do that since it is only 1/2 inch wider plus the higher offset doesn't visually make a difference as long as the tire sizes are the same.

Using 245 all around for this particular setup just gives you more flexibility when you rotate the tires.
For the record, tire thread patterns also play a central role in how you can rotate the tires.

maisinh

Thanks for your very educational answers. I can understand about the wheel now. Whenever you have time please educate me more about "the tire thread patterns also play a central role in how you can rotate the tires". Don't forget i am the one who has a lot of things that "want to know but afraid to ask" (just dont want to be yelled at). Once again, thanks your patience.
P.S How do you know so much a bout the car??

BNR34

iTrader: (1)

Yes it would look similar to that, it would bulge out quite a bit. It would fit, but I don't like that look anymore. It is like the old muscle car look, tires way wider then the rim look.

BNR34

iTrader: (1)

It would fit, but it would bulges out a lot. I too suggested running a 255/40 on that 8.5.

BNR34

iTrader: (1)

I was just saying it would be a bit more stretched compare to the front 245 on 8, but yeah it is not much.

I would take that 1.25% off

The tire store recommended 275 on that 8.5

I had 265 on 8.5 on my last car and I loved how it looks and performed. Then I went to a 275 and it got too wide.