Seat Leon Tyre Size

[sparkster86]

Hi guys,

I have a 2018 Leon FR 1.4 TSI. I brought the car a few years ago and it had 245/45/R18 tyres on it but I have seen online that most places come back with 225 size tyres when I put in my reg.

Can anyone advise? Am I running wrong sizes? Is it just a simple change of tyre?

Thanks

 

[serdar_18fr]

Hi guys,

I have a 2018 Leon FR 1.4 TSI. I brought the car a few years ago and it had 245/45/R18 tyres on it but I have seen online that most places come back with 225 size tyres when I put in my reg.

Can anyone advise? Am I running wrong sizes? Is it just a simple change of tyre?

Thanks

The original tyre size for 18" wheels on Leon Mk3s is 225/40.

 

[SRGTD]

@sparkster86; as @serdar_18fr has said, the tyres fitted by Seat to 18” alloys on the mk3 / mk3.5 Leon were 225/40 R18.

It could be that a previous owner of your car found the ride on the standard tyres to be too firm for their liking so they changed them to a set with wider tread and higher sidewall with greater compliancy. However, 245/45 R18 tyres will have a larger rolling radius (and therefore circumference) than the OEM tyres which results in a speedo reading error (see below); speedo will under-read by circa 5.5% so at a true 60 mph the speedo will be showing 56.7 mph, and when the speedo is showing an indicated speed of 60 mph, the driver will be unwittingly exceeding the speed limit.

Be aware that in the UK although it’s legal for a car’s speedo to over-read by up a predefined amount, it’s illegal for it to under-read by any amount - see the last section of the article at the link below (The law for car speedo,enters in the UK);

https://www.thecarexpert.co.uk/how-accurate-is-a-car-speedometer/

 

[sparkster86]

@sparkster86; as @serdar_18fr has said, the tyres fitted by Seat to 18” alloys on the mk3 / mk3.5 Leon were 225/40 R18.

It could be that a previous owner of your car found the ride on the standard tyres to be too firm for their liking so they changed them to a set with wider tread and higher sidewall with greater compliancy. However, 245/45 R18 tyres will have a larger rolling radius (and therefore circumference) than the OEM tyres which results in a speedo reading error (see below); speedo will under-read by circa 5.5% so at a true 60 mph the speedo will be showing 56.7 mph, and when the speedo is showing an indicated speed of 60 mph, the driver will be unwittingly exceeding the speed limit.

View attachment 54865

Be aware that in the UK although it’s legal for a car’s speedo to over-read by up a predefined amount, it’s illegal for it to under-read by any amount - see the last section of the article at the link below (The law for car speedo,enters in the UK);

https://www.thecarexpert.co.uk/how-accurate-is-a-car-speedometer/

Thank you for the input.

Do you think I just need to change the 4 tyres back over to 225/40/R18 then? Or do I need to get the wheels checked for size also?

 

[serdar_18fr]

Thank you for the input.

Do you think I just need to change the 4 tyres back over to 225/40/R18 then? Or do I need to get the wheels checked for size also?

The wheels are obviously 18". If they are not original SEAT ones, the other measurements of concern are width of the wheel, ET value and center bore diameter.

Original SEAT 18" alloys are 7.5" wide, has a 51mm of ET value for that width, and 57.06mm as center bore diameter.

Exact-sized aftermarket alloys are available but there's limited choice with those. Many 18" aftermarket alloys are of different width, ET or center bore diameter. Those could be used with care, but all of those values -singularly or combined- would have some adverse effect on suspension geometry and clearance if there's too much of difference.

 

[sparkster86]

The wheels are obviously 18". If they are not original SEAT ones, the other measurements of concern are width of the wheel, ET value and center bore diameter.

Original SEAT 18" alloys are 7.5" wide, has a 51mm of ET value for that width, and 57.06mm as center bore diameter.

Exact-sized aftermarket alloys are available but there's limited choice with those. Many 18" aftermarket alloys are of different width, ET or center bore diameter. Those could be used with care, but all of those values -singularly or combined- would have some adverse effect on suspension geometry and clearance if there's too much of difference.

Thanks so i think i need to get a new set of 225/40/R18's then

 

[serdar_18fr]

Thanks so i think i need to get a new set of 225/40/R18's then

And you might want to post a photo of your alloy wheels if you're not sure whether they are original SEAT ones (or at least replicas of them) so we can help about that too.

 

[sparkster86]

And you might want to post a photo of your alloy wheels if you're not sure whether they are original SEAT ones (or at least replicas of them) so we can help about that too.

Ok i will get a photo thank you

 

[sparkster86]

And you might want to post a photo of your alloy wheels if you're not sure whether they are original SEAT ones (or at least replicas of them) so we can help about that too.

Photo attached

 

[Mo_86]

Photo attached

Those are facelift fr alloys so should be 225 40 18