tyres

[Andrew63]

hi people

im a wee bit confused.

continental tyres we have 255/35/18 fitted to the rear on our car! 10,000miles and dead

the front tyres are 225/45/18 as far as I'm concerned these are correct for my car

question is can I change the rear tyres for 255/45/18. without upsetting the abs.

foumula 1 refused to replace the tyres stating that the tyres are incorrect for my car

the suggestion from them was that 225/45/18 is a different diameter to 255/45/18 subsequently after a brief debate the tyres have been proven to be the same size (formula 1 wrong) however for a bit more comfort and economy i took the decision to go with the 255/45/18.

f1 duly noted the car would have been set up with the 255/35/18 (smaller diameter ) so it could effect the abs.

do i risk it or revert back to the original size.

after a day spent browsing there appeares to many variants of wheel sizes mixing odd sizes.

hence "im confused"

who can help

 

[Andrew63]

hi people

im a wee bit confused.

continental tyres we have 255/35/18 fitted to the rear on our car! 10,000miles and dead

the front tyres are 225/45/18 as far as I'm concerned these are correct for my car

question is can I change the rear tyres for 255/45/18. without upsetting the abs.

foumula 1 refused to replace the tyres stating that the tyres are incorrect for my car

the suggestion from them was that 225/45/18 is a different diameter to 255/45/18 subsequently after a brief debate the tyres have been proven to be the same size (formula 1 wrong) however for a bit more comfort and economy i took the decision to go with the 255/45/18.

f1 duly noted the car would have been set up with the 255/35/18 (smaller diameter ) so it could effect the abs.

do i risk it or revert back to the original size.

after a day spent browsing there appeares so many variants of wheel sizes mixing odd sizes.

hence "im confused"

who can help

 

[Rotorhead500]

I'm on my phone, so can't see all your info... but if it's on a C250, then the 255 width doesn't sound standard for 18s?

 

[richlumb]

Look at the tyre pressure label (in the filler cap I think) it gives the tyre sizes , but my c250 had 18” 225/45 fronts and 255/35 rears (but may have been 255/40 )

 

[AMGeed]

If you have a staggered set up which it appears you do as you have wider tyres on the rear if the front tyres are 45 profile you need 40 profile on the rears.
Either 245 or 255 would fit.

 

[sonic]

Mercedes-Benz Fitting Chart and Wheel Fitment Guide | Alloy Wheels Direct

Comprehensive wheel fitting chart and guide for Mercedes. Information on tyre and wheel sizes, offsets and PCDs. Find out which wheels will fit your vehicle

www.alloywheelsdirect.net

 

[JBell]

You should have:

front: 225/45R18 95Y XL
rear: 245/40R18 97Y XL

 

[Flyinspanner]

The second figure is a % wall height, expressed against the width of the tyre.
so 225/40/18 will have the same diameter (near enough) as 245/40/18.

this is completely normal and correct for ‘staggered’ wheels.

Formula 1 were correct.

 

[Andrew63]

Look at the tyre pressure label (in the filler cap I think) it gives the tyre sizes , but my c250 had 18” 225/45 fronts and 255/35 rears (but may have been 255/40 )

hi there i have the c250 premium plus if that makes any difference i think they should be the 255/35/18 but can i put the 255/45/18s on this car

theres not indication in the fuel cap cover other than pressures.

 

[Andrew63]

The second figure is a % wall height, expressed against the width of the tyre.
so 225/40/18 will have the same diameter (near enough) as 245/40/18.

this is completely normal and correct for ‘staggered’ wheels.

Formula 1 were correct.

ok but using the tyre calculator they offered a 225/45/18 has the same diameter as a 255/45/18 (exactly) so can i fit the latter without abs issues

 

[Andrew63]

I'm on my phone, so can't see all your info... but if it's on a C250, then the 255 width doesn't sound standard for 18s?

yes c 250 premium plus according to mb 255/35/18 should be the rear tyres that i understand but can i fit 255/45/18 to increase comfort level without abs issues

 

[curious]

There are a couple of concerns with putting non-standard size tyres on a vehicle.
The first you've already discovered is that reputable tyre fitters won't do it.
The second is that unless you get approval from your insurance company for your modification, your insurance could be invalid.

 

[EmilysDad]

ok but using the tyre calculator they offered a 225/45/18 has the same diameter as a 255/45/18 (exactly) so can i fit the latter without abs issues

typo?

 

[Flyinspanner]

ok but using the tyre calculator they offered a 225/45/18 has the same diameter as a 255/45/18 (exactly) so can i fit the latter without abs issues

That is a mathematical impossibility.

225/45/18= 26” dia, 81.6” circ and will rotate 777times per mile.

255/45/18=27”dia, 84.9”circ and will rotate 746 times per mile

your Speedo will underread, and as mentioned above your insurer May wriggle out of any claim if it’s not a listed size/option for your car.

 

[Andrew63]

good evening folks thanks for the clarification

im now happy with 245/40/18 that apparently should be the size fitted to the rear and 225/45/18 of the front of my car

finally someboby who knows thanks guys

 

[sonic]

ok but using the tyre calculator they offered a 225/45/18 has the same diameter as a 255/45/18 (exactly) so can i fit the latter without abs issues

I don't think you can get a 255 profile on to a 225 rim.

 

[Andrew63]

There are a couple of concerns with putting non-standard size tyres on a vehicle.
The first you've already discovered is that reputable tyre fitters won't do it.
The second is that unless you get approval from your insurance company for your modification, your insurance could be invalid.

yes got it

apparently last year my brotherinlaw ad buget tyres fitted to his boxter after a series of problems he had to have all his tyres changed to approved tyres or his insurance would have been void

after one of your colleagues sent a data sheet i can now actually see what should have been fitted in the first place.

thanks all

 

[Andrew63]

I don't think you can get a 255 profile on to a 225 rim.

the 255/35/18s had been fitted to the car two years ago nice grip but disappointing mileage just 10000 and thats with the wife driving back and forth to school. (continentals)

 

[Andrew63]

That is a mathematical impossibility.

225/45/18= 26” dia, 81.6” circ and will rotate 777times per mile.

255/45/18=27”dia, 84.9”circ and will rotate 746 times per mile

your Speedo will underread, and as mentioned above your insurer May wriggle out of any claim if it’s not a listed size/option for your car.

just done the same calculations 225/45/18 rev 483 per km 255/40/18rev 482 per km thats far closer than the previous tyres
so my old tyres which are 255/35/18 rev 501 per km looks like humble pie to formula 1 tomorrow

 

[Andrew63]

I don't think you can get a 255 profile on to a 225 rim.

yes you can ive apparently had the wrong tyres fitted all along grip well tho now shot after 10000 miles