Rear end sitting higher than front

[BillNick]

Hi all,

We all know the rear end sits up a slightly higher with the nose pointing down - I wanted to know if this was purely down to the different tyre sizes or is suspension at play here also?

I have 18" ISP MODE alloys ready to go on and am choosing tyres.

I'd quite like to get my car sitting level. Can I achieve this choosing the right tyres or would I need to fiddle suspension also??

[Verbout]

The cheap option would be to park it on a hill

Sorry.

A sensible person will be along shortly.

[johnatg]

It is just how the majority of modern mid-range sports saloons are styled these days. The idea is to give a low 'sporty' front end whilst providing decent boot capacity. I think you will find that the gaps between tyres and wheel arch tops are pretty much even front/rear and the bottom of the sills are level with the ground. Any attempt to re-orientate it by fiddling with tyres/wheel sizes will upset those parameters and make it look very odd.

[BillNick]

I guess for me the deeper tyre walls make it more apparent.

What are the standard tyre sizes for the 18" F Sport rims?

Is it true to get the measurement of a tyre wall you use the profile number as a % of the tyre width?

eg 255/35/18 the tyre wall would be 35% of 255 = 89.25??

[johnatg]

Yes - pretty much - in mm - forget the decimal places!

You don't mention what rim width your wheels are - standard tyre sizes for 18" rims (I think this will apply to F Sport models as well as others) are 225/40R18 and 255/40R18. But that is with 8" rims on the front and 8.5" rims on the rear. Don't put 255 tyres on 8" rims - you need at least 8.5" rims for them, and preferably 9".

BTW - my comments in the post above apply also to fiddling with the suspension - probably even more so.

[BillNick]

I have 2x 18x8 for the front and 2x 18x8.5 for the rear

[Linas.P]

On 7/26/2016 at 9:40 AM, Billnick said:

I have 2x 18x8 for the front and 2x 18x8.5 for the rear

That is correct assuming you have original Lexus wheels, so it would be correct to stick with original the tire sizes as well - 225/40R18 and 255/40R18. Now that said I guess you can achieve "lower looking" rear end with using narrower tires in the rear, which will make them "stretched" a bit, would make overall rolling radius smaller and rear end visually more level with the front. However, as mentioned by others it would upset the setup and I would not recommend anything less than 245 on the rear. 

[BillNick]

What if I went 255/35/18 on the rear? I guess it's only a difference of approx 10mm (35 vs 40 profile) so prob not worth messing with the setup.

I will have a proper look tonight, but although I can clearly see that the rear sits up, I have not paid any attention to the sills....if the sills are level with the road then the body has been purposely shaped to sit on a higher rear end and lowering the rear would look even worse haha

[Linas.P]

That is exactly what it is .. the car is taller in the rear and kind of pointy in the front. The reason why many people pick up rear wheels as the issue is not really the radius of the wheels, but because Lexus decided to have staggered not only rims but as well tires. Therefore, rear tires are kind of squared while front ones looks stretched. This is as well reason why I am suggesting narrower rears, so that both rears and fronts would look more similarly stretched.. rather than having that completely horizontal side wall only on rears. This is especially noticeable on 18 set-up, little bit less on 17 inch.