Hi all,

 

Apologies if this has already been discussed, I did try searching the forum and not found anything specific to my case.

Looking at buying some Bridgestone Turanza's 6 for my car.

My car is a Skoda Superb 2.0tdi L&K 2016 

 

Price for 4 tyres 235/45/18 is £510 from Costco (This is what is currently on the car and the correct tyre)

 

Price for 4 tyres 225/40/18 is £265 from Costco.

 

Now my cheap ass is thinking, that's nearly half the price off.

IS this a terrible idea? will it spoil the drive of the car.

Any advice would be appreciated.

 

Thanks

surely that will change the rolling circumference .......

While looking at prices it is easy to look at size comparisons and see why some changes are just not on. 

"Will they fit" is a great website fir this sort if thing.

 

Assuming your insurance co are happy with it there are technical issues with changing to such a different size.

Rolling circumference is roughly 5% smaller meaning the wheel will rotate faster for a given car speed (speed over land, not speed on the speedometer).  For the same speed on the speedo, the car will be travelling slower.  The speedo is connected to the rotating parts of the car (usually front wheel axle in some way). If you drive to the GPS speed then you will rack up more miles on the car than it has actually done.

The ride height will be nearly 16mm lower.  This could give better anti roll due to lower center of mass.  It also will give less ground clearance.

The ride will be less comfortable.  More so than the standard 19s which uses the same profile tyre as the diameter is smaller.  This means it won't roll over things as well thus feeling more of the imperfections.

Apart from cost, the only benefit is greater acceleration due to lower gearing from the smaller outside diameter.

 

My final word?  I wouldn't.

^^^ aside of the legal (illegal I believe) implications ..............

 

Even if the tyre sizes mentioned have been mixed up by the OP

 

ie 235 x 40 ............ vs .......... 225 x 45 ......... is still a circa 7mm difference in sidewall height.

Sidewall height is not really the issue.  (Well it is here with the same size rims being used.) 

The difference in Total Diameter / Circumference is what matters.

8 minutes ago, Tilt said:

^^^ aside of the legal (illegal I believe) implications ..............

 

 

I don't think it's a legal matter as long as the car is road worthy.  However, if your insurance co don't like it they can void your policy thus leaving you driving illegally with no cover.  So it's an indirect legal issue.

HI all,

 

Thanks for the great responses.

By the look of things, it doesn't seem like the £250 saving is worth the extra hassle. Will probably stick to the original fitment and bite the bullet.

1 hour ago, gidi19 said:

IS this a terrible idea?

Emphatically YES,

Bad idea - I wouldn't do it for the reasons above.

Edited 12 February, 20251 yr by JR RS

Can anyone recommend a tyre make?

Im reading mix reviews about the Bridgestone turanzas I was going to buy.

I'm after comfort and low road noise. 

Just wondering what other members have put on their cars and how they have found them.

There are too many interesting, but sparse, threads on tires. Somewhere else is written 245/45 it seems a reasonable option.

I am also uncertain as I will go 18s this season.

7 hours ago, leolito said:

There are too many interesting, but sparse, threads on tires. Somewhere else is written 245/45 it seems a reasonable option.

I am also uncertain as I will go 18s this season.

There are also lots of references to "will it fit" websites.

19 hours ago, gidi19 said:

Can anyone recommend a tyre make?

Im reading mix reviews about the Bridgestone turanzas I was going to buy.

I'm after comfort and low road noise. 

Just wondering what other members have put on their cars and how they have found them.

 

I guess you are going to get mixed reviews on EVERY tyre hat you look at, wherever you look at them.

 

Tyres do give you a dB rating so if you can find one at 67dB then that should be about the quietest ......... HOWEVER I do not think you will find one with that rating in the size of tyre you are looking at.

You may find some around 70/71dB but a lot depends on your car's own sound insulation and suspension set up very much.

 

If you are lucky, you may just be in the size range to look at tyres with specific sound reducing technology implemented in it's manufacture.

 

For instance

https://www.goodyear.eu/en_gb/consumer/why-goodyear/soundcomfort-technology.html#:~:text=The rolling noise of the,big difference in noise levels.

And I would have thought softer tyres would be quieter than hard tyres, but IIRC there are many opposing opinions on that too.

Certainly wouldn't fit the smaller size tyre. That will ruin the ride and leave you at danger of kerbing your wheels, or buckling them on the potholes that are everywhere.

Secondly, and it's only my opinion, I would not buy Bridgestone tyres, ever. My Karoq came with them at between 4mm and 6 mm. They were promptly replaced with vredestien winters and I run a different set of wheels in summer with kormoran summer tyres. They are apparently made by Michelin an are good on my karoq.

Michelin own the company that makes Kormoran, like they own the ones that make BF Goodrich / Uniroyal Goodrich, TIGAR, Riken, Kleber and maybe more.

Various Countries and Companies.  (used all of these at one time or another, fitted at ATS Euromaster.)

& the own ATS Euromaster & BlackCircle. 

Edited 15 February, 20251 yr by Ootohere

Another for not fitting the smaller tyre size. It'll ride rough and they'll be a bit stretched. 

 

As for tyres you'll get plenty of mixed opinions. Currently on Davanti's which are ok, I had Michelin PS5's before which are my go to. I've also run Goodyear Eagle Asymmetric 5's which were similar to the Michelin's.  

 

Looking on Blackcircles you could get the Goodyear Asymmetric 5's for £154 each, but for the cost the Bridgestones seem good, especially if you have been happy with them. 

 

Check 235/45/19's if you arnt so worried about tyre profiles. They'll be taller and that'll cause your speedo to be out but may be a bit cheaper per tyre. 

10 hours ago, Dooge said:

Check 235/45/19's if you arnt so worried about tyre profiles. They'll be taller and that'll cause your speedo to be out but may be a bit cheaper per tyre. 

 

If hunting for alternate sizes, I would suggest a change 235 to 245 rather than 40 to 45 profile.  The profile is a percentage of the width.  Adding a small amount to the width makes it wider and taller.  This add comfort and rim protection without putting the speedo out too far.

4 hours ago, MarkyG82 said:

 

If hunting for alternate sizes, I would suggest a change 235 to 245 rather than 40 to 45 profile.  The profile is a percentage of the width.  Adding a small amount to the width makes it wider and taller.  This add comfort and rim protection without putting the speedo out too far.

I was saying more from a cost point of view as the 45 profile are cheaper than the 40 without massively affecting look or ride. 245's are a good step in price over a 235 and will be a bit more draggy I'm guessing. 

8 hours ago, Dooge said:

I was saying more from a cost point of view as the 45 profile are cheaper than the 40 without massively affecting look or ride. 245's are a good step in price over a 235 and will be a bit more draggy I'm guessing. 

 

That's not true as it varies between different sizes such as 17, 18, 19, 20 etc etc.

 

Here in Oz, 245/40/19 tyres r much more cheaper than 235/40/19 tyres.

That's because the 245/40/19 tyres r a lot more common and more widely used by other manufacturers, compared to 235/40/19.

 

Hence why many of us have switched to 245/40/19 tyres.  Thicker sidewall and wider footprint is a win win.

 

235/40/19 is the standard size for mk3 Superb with factory 19s.

12 hours ago, JR RS said:

 

That's not true as it varies between different sizes such as 17, 18, 19, 20 etc etc.

 

Here in Oz, 245/40/19 tyres r much more cheaper than 235/40/19 tyres.

That's because the 245/40/19 tyres r a lot more common and more widely used by other manufacturers, compared to 235/40/19.

 

Hence why many of us have switched to 245/40/19 tyres.  Thicker sidewall and wider footprint is a win win.

 

235/40/19 is the standard size for mk3 Superb with factory 19s.

Noted, but the original poster is in the UK and thats where I was looking...

The op should go look at 235/50×18. That's the size I run on my summer tyres and I need two replacing before these go on and the prices I am seeing are not too bad. 

21 hours ago, Dooge said:

Noted, but the original poster is in the UK and thats where I was looking...

Also here in southern latitudes - well, not so "south" as JR 😜 - 245s are cheaper.

 

The op should go look at 235/50×18. That's the size I run on my summer tyres .....

I am inclined to /50 on 18s for mine, unsure if on 225 or 235 though. I do not like too wide tires, I got too much tramlining on the crappy roads that are here ...

20 hours ago, daviemck2006 said:

The op should go look at 235/50×18. That's the size I run on my summer tyres and I need two replacing before these go on and the prices I am seeing are not too bad. 

 

That's an interesting thought.  Not such a drastic change compared to OPs original question and also in a more positive direction.  The norm is to stick within 3% of the oem size and this is over that (3.39%) if sticking with 235 width.  Maybe dropping to 225 as @leolito suggests is a good idea.  Less draggy and more comfort.  Although you do lose some rim protection.