Tyre size C43

[amg3.6]

I'm upgrading my wheels on my c43 amg to 18" im thinking of putting tryre sizes 225 40 18 on the front and 245 40 18 on the rear is this ok?

ive been told to go wider on the rear to either 255 or 265 would this be wise or not? and another question on profile should i leave them 40 all round or go 40 on the front and 35 on the rear?

I dont want to go to low in profile so that i have to drop the car

 

[Gridlock]

225 40 18 on the front and 245 40 18 on the rear

That would give you differing diameters front and rear, the fronts should be 45.

 

[vijilants]

should i leave them 40 all round or go 40 on the front and 35 on the rear?

Id stick with the same profile front and rear. Also 35 is probably going to give you a very hard ride

 

[amg3.6]

Ive currently have 40 all round but they are 17"

 

[noops]

Ive currently have 40 all round but they are 17"

I've got 225/40/18 at the front and 255/35/18's at the back, looks good and the ride is comfortable.

 

[andy27168]

Hi,
The standard rolling radius has to be maintained regardless of what diameter wheels you are using this so the traction/ABS and cruise all operate correctly.
If you are going up a wheel size from standard, go to the next size down in profile to what your standard tyres were.

 

[amg3.6]

H andy what if i went 225 40 18 on the front and 255 35 18 on the rear? i dont want to go to low in profile as the ride will be hard

 

[renault12ts]

Look guys, the tyre's profile is a percentage of the tyre's width. Thus if you have different width tyres front and rear but the same profile (say 40) then the rear tyres will be too tall compared to the front. The cruise control and other systems may not work properly. So if you go wider at the rear you also go to a lower profile number (this is not a lower tyre just one that's the same height more or less as the front).

225/40 has a tyre wall height of 90 mm. 245/40 is 98mm. The rear tyre needs to be 255/35 giving a tyre wall size of c89mm.

 

[renault12ts]

Id stick with the same profile front and rear. Also 35 is probably going to give you a very hard ride

Why do you think this?

 

[renault12ts]

Ive currently have 40 all round but they are 17"

I presume the tyres are also the same width front and rear?

 

[renault12ts]

I've got 225/40/18 at the front and 255/35/18's at the back, looks good and the ride is comfortable.

These are correct. Tyre walls of 90mm and 89mm respectively, they within tolerance.

 

[RBYCC]

H andy what if i went 225 40 18 on the front and 255 35 18 on the rear? i dont want to go to low in profile as the ride will be hard

They are the recommended sizes to be used for a staggered 18x8.5 ET32 front and 18x9.5 ET35 rear setup.
I've had them on my wife's C43 for 2 years and no problem with ride quality using Falken FK452's.

Ed A.

 

[robertc43]

I've got 225/40/18 at the front and 255/35/18's at the back, looks good and the ride is comfortable.

My C43 has been running this setup for years and no problems to report.

 

[renault12ts]

My C43 has been running this setup for years and no problems to report.

'cause that's the correct set up.

 

[renault12ts]

Which of these has the lower tyre wall 145/70 or 290/35 ??

 

[vijilants]

Why do you think this?

Well, moving from a vehicle that was designed to run on 17in wheels to 18in wheels with low profile tyres such as 35's would definately give a harder ride simply because you have less of a cushion between the wheel rim and the road.

I know for sure that when I moved from 16's to 17's and dropped the profile it definately gave me a harder ride.

Im not saying this would cause a problem, but for sure the ride will harden. The lower the profile tyres also give less sidewall movement, hence it does change the ride.

Tyre profile does change the characteristics of suspension behaviour.

Have a drive around the potholed roads in London and I'm sure that you will notice the difference

 

[rees_A]

I've jot 225/40/18 and 265/35/18 on my CLK55

 

[Londonscottish]

Well, moving from a vehicle that was designed to run on 17in wheels to 18in wheels with low profile tyres such as 35's would definately give a harder ride simply because you have less of a cushion between the wheel rim and the road.

I know for sure that when I moved from 16's to 17's and dropped the profile it definately gave me a harder ride.

Im not saying this would cause a problem, but for sure the ride will harden. The lower the profile tyres also give less sidewall movement, hence it does change the ride.

Tyre profile does change the characteristics of suspension behaviour.

Have a drive around the potholed roads in London and I'm sure that you will notice the difference

+1

I has 35 profiles on my last 200SX which were pretty brutal over London potholes and speed bumps.

The C43's had a mix of 45's at the front IIRC and 40's at the back. (Or was it 40' at the front and 35's at the back?) Anyway the rears used to bang and crash about on the worse tarmac.

My E500 has 45's all round. Much better.

Obviously, I am turning into my Dad.

 

[renault12ts]

But the point is that 35 is a ratio. A wider tyre will still have a deeper side wall than a narrower tyre given the same aspect ratio. So in my post (15) above the answer is the same. They both have tyre wall depths of 101.5mm. So you can't say that all 35% tyres are harsh, it depends on the tyre width.

So in the OP's question about tyres and aspect ratios, if you have wider tyres at the rear you MUST have lower aspect ratios also. This will mean that the rolling circumference of the tyres are kept very close together. Thus the CC and other equipment will work the way they are supposed to.

And if you go from 17" to 18", then all tyres must have a lower aspect ratio (if the tyre width remains the same).

 

[RBYCC]

Well, moving from a vehicle that was designed to run on 17in wheels to 18in wheels with low profile tyres such as 35's would definately give a harder ride simply because you have less of a cushion between the wheel rim and the road.

I know for sure that when I moved from 16's to 17's and dropped the profile it definately gave me a harder ride.

Im not saying this would cause a problem, but for sure the ride will harden. The lower the profile tyres also give less sidewall movement, hence it does change the ride.

Tyre profile does change the characteristics of suspension behaviour.

Have a drive around the potholed roads in London and I'm sure that you will notice the difference

More to the equation then the profile/cross section of the tyre.
The width of the wheel is a major contributor.
Optimum performance is attained by using a tire that matches the measured rim width.
Narrower rim softens sidewall, wider rim stiffens sidewall..

The ride quality is not the same for all brands of tires.
Some give a much harsher ride then others..
I find the 18" Falken FK-452's do not degrade ride quality over the stock 17" tires.