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Leon ST 18" tyre sizes?

TripleBob

Active Member
May 3, 2021
311
201
Apologies if this has been asked before, tried searching and couldn't see anything concrete!

I've bought a 2018 Leon FR ST, which I'm due to collect early next week - I already know (and factored into the negotiated purchase price) that it needs new tyres, as the current ones are mismatched budgets - albeit with decent tread left on them.

My plan is to immediately fit Pilot Sport 4's all round (seems a popular choice on here?), But like a complete idiot I forgot to actually make a note of the tyre size/rating

The cars on the optional 18" FR sports wheels - I've tried a few 'look up your tyre size by reg' sites and they unhelpfully all give different sizes - anything from 225 to 245, and 35-45

Does anyone know what size I should be looking at that won't mess up the Speedo accuracy?

Many thanks!
 

Mr Pig

Active Member
Jun 17, 2015
2,705
953
I put four PS4s on out estate not long ago. You won't be disappointed, they are great tyres.

Cheapest place I found was Camskill. Someone on here flagged up a sale on them but I looked back and they have sales regularly. I got £60 off a set of four.
 
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TripleBob

Active Member
May 3, 2021
311
201
Cheers, current best offer is on black circles works out at £87.51 per tyre fitted - will keep an eye on camskill!
 

Mr Pig

Active Member
Jun 17, 2015
2,705
953
Cheers, current best offer is on black circles works out at £87.51 per tyre fitted - will keep an eye on camskill!
They seemed to run a Michelin promotion every other month. Might be worth asking them about it.
 

black_sheep

Active Member
Mar 10, 2013
1,255
586
They seemed to run a Michelin promotion every other month. Might be worth asking them about it.
Black circles is owned by Michelin - you would hope that they would push their own products regularly ;-)

Costco is another outlet that generally has 3 monthly cycle of £50 off 2 and £100 off 4 tyres.
 
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Big Col

Active Member
Nov 5, 2013
626
89
North Ayrshire
tyre review of 225/40-18's


I was looking for 4 tyres this time last year and went for the F1A5's. Have used the PS4 in the past, the F1A5 is every bit as good.

With the launch of the GR Yaris - which comes with the Michelin PS4S in 225/40-18 - I've heard Michelin are now making this tyre available in the UK. Might be worth looking for these in place of the normal PS4.
 
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TripleBob

Active Member
May 3, 2021
311
201
Thanks for all the recommendations, I'll be honest up until now I've always used Rainsport 3's on my old car (5s weren't available in that tyre size) - I'm assuming F1's or PS4's are considered better in this size?
 

Leeon

Active Member
Sep 4, 2014
29
10
Having only had my motor a couple of weeks I seem to have 225/45/18. Whether this was because the car has coilovers I dunno. So anyway when going through speed traps or GPS on Google maps my Speedo matches exactly. I have never had a car that does that, all previous the Speedo was a like 10% under.

Sent from my SM-G986B using Tapatalk
 

rafletcher

Active Member
Feb 18, 2021
531
214
Having only had my motor a couple of weeks I seem to have 225/45/18. Whether this was because the car has coilovers I dunno. So anyway when going through speed traps or GPS on Google maps my Speedo matches exactly. I have never had a car that does that, all previous the Speedo was a like 10% under.

Sent from my SM-G986B using Tapatalk
You have a tyre with a greater rolling circumfernce fitted to your car than it was designed for. That means (using a tyre calculator) your car is actually travelling at 3% greater speed than expected (ie, you'll be doing 31 instead of the expected 30). If you had the correct (40 profile) tyre fitted, your speedo would read 30 when you were doing 29.8 - under-read by around 3%, which is how it should be. It's illegal for speedos to indicate a lower speed than your actual one, and all car manufacturers make sure the accuracy is +0 -10%, which is the law in the UK. Practically I guess it makes little difference, at least while UK speed enforcement allows a margin above the posted limit before deciding you've committed an offence. In France the enforcement limits is set at the actual limit, so there, at higher speeds, you could be in trouble, at least on new tyres.
 
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Leeon

Active Member
Sep 4, 2014
29
10
You have a tyre with a greater rolling circumfernce fitted to your car than it was designed for. That means (using a tyre calculator) your car is actually travelling at 3% greater speed than expected (ie, you'll be doing 31 instead of the expected 30). If you had the correct (40 profile) tyre fitted, your speedo would read 30 when you were doing 29.8 - under-read by around 3%, which is how it should be. It's illegal for speedos to indicate a lower speed than your actual one, and all car manufacturers make sure the accuracy is +0 -10%, which is the law in the UK. Practically I guess it makes little difference, at least while UK speed enforcement allows a margin above the posted limit before deciding you've committed an offence. In France the enforcement limits is set at the actual limit, so there, at higher speeds, you could be in trouble, at least on new tyres.
Good to know, I wonder how much that extra 5mm is impacting the ride firmness, its pretty firm already
 

rafletcher

Active Member
Feb 18, 2021
531
214
The fact you haver a higher profile (45) tyre means it's more comfortable than a 40 profile tyre :).
 

TripleBob

Active Member
May 3, 2021
311
201
I'm coming from a 215/50/R17 on my old car - hopefully the 40 profile will be comfy for motorway cruising, felt well damped on the test drive - but my old car was dropped 35mm!
 

Mr Pig

Active Member
Jun 17, 2015
2,705
953
I'm assuming F1's or PS4's are considered better in this size?
I have F1s on the back of one car but can't really tell how good they are. Need to wait until they're on all for corners.

The other car has the PS4s on and those tyres are the dogs. If you can afford them, buy them. Easily the best tyre I've used. Even I the dry the extra grip is noticeable and they have good 'feel' to them.
 

andylong

Active Member
Jan 21, 2021
494
1
134
It's worth noting that the flexing part of the sidewall, the part that affects comfort in this thread is the part that gets smaller and the tread part and bead part stay the same as you reduce the profile. This means that the harshness of ride will be increased significantly more from 45 to 40, than from 50 to 45.

Your tyre gets increasingly vulnerable as the profile lowers and I would advise against purchasing lower profile tyres for cosmetic reasons.
 

TripleBob

Active Member
May 3, 2021
311
201
It's worth noting that the flexing part of the sidewall, the part that affects comfort in this thread is the part that gets smaller and the tread part and bead part stay the same as you reduce the profile. This means that the harshness of ride will be increased significantly more from 45 to 40, than from 50 to 45.

Your tyre gets increasingly vulnerable as the profile lowers and I would advise against purchasing lower profile tyres for cosmetic reasons.

Wont be for cosmetic reasons, the car I've bought has 18" wheels as standard from the factory - I just wanted whatever size was needed to not mess the speedo accuracy up! I often drive in Europe, so need to make sure I'm under reporting not over...

Have ordered PS4's in 225/40/R18 (XL) now, thanks everyone for suggestions!
 

rafletcher

Active Member
Feb 18, 2021
531
214
Wont be for cosmetic reasons, the car I've bought has 18" wheels as standard from the factory - I just wanted whatever size was needed to not mess the speedo accuracy up! I often drive in Europe, so need to make sure I'm under reporting not over...

Have ordered PS4's in 225/40/R18 (XL) now, thanks everyone for suggestions!
My bold. I use this website wehn comparing tyres... https://www.willtheyfit.com/
 
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