Winter Tyre Pressure question 235/40/19 tyres

[rafletcher]

So, today I picked up a set of winter tyres for my Cupra Ateca. Now, I have a “Limited Edition” version, and that comes with 20” rims as standard, and the only tyre pressure information provided on the door pillar relates to 20” tyres 42/39psi unladen.

The winter wheels and tyres I have acquired are 19” (yes, a 19” rim does clear the Brembo brakes) the tyre being 235/40/19 - and off an Ateca (that tyre size is one that can be fitted to the 2.0 TSi 4-Drive variant as standard).

My question is, what would the recommended pressures be for 235/40/19 tyres? The handbook, of course, just says “look at the door pillar”.

And yes, I checked with my insurers that they would allow fitting appropriate winter tyres when I took out the policy.

 

[RUM4MO]

Add 0.1Bar or 1.5PSI to any summer tyre that size replies that you get, that is the general advice - but there again 0.1Bar /1.5PSI is not much change from normal pressure.

 

[rafletcher]

If they were the same tyre size, maybe, but they’re not, I’m down in rim size and up in sidewall height, and that, due to the increase in air volume in the tyre, dictates a lower pressure so the “load” on the tyre remains similar. Hence my wanting to know what the usual 40/19 tyre pressures are

 

[RUM4MO]

Yes I understand that and that is why I included "Add 0.1Bar or 1.5PSI to any summer tyre that size replies that you get" in my reply!

 

[rafletcher]

Well yes - but what’s the summer pressure!

 

[RUM4MO]

Well yes - but what’s the summer pressure!

That is for another owner who is on this forum to hand over to you, I was just adding in the "winter" extra pressure info as most people probably don't use winter tyres like you plan to and I have been doing for many many years.

 

[Glosphil]

My Nokian winter tyres recommend 3psi over summer pressures (for same size tyres). I found this causes the winter tyres to wear more in the centre of the width of the tyres which usually indicates over-inflation!

 

[RUM4MO]

My Nokian winter tyres recommend 3psi over summer pressures (for same size tyres). I found this causes the winter tyres to wear more in the centre of the width of the tyres which usually indicates over-inflation!

Ah, maybe the "curse" of checking across the tyres - I'm afraid I tend to do that as well - makes a lot of sense!

Still no absolute answers for the OP, but I run my " -1 inch" winter tyres between 2 and 3PSI higher than the summer tyres. That is for 19" down to 18" on an S4.

Also, as said by @Glosphil, check them when they get swopped to make sure that the wear is roughly even across the width and if not reassess the pressures used - same for summer wheels when they come off, I tend to inflate to 41PSI when being stored.

 

[cupraatecastu]

So, today I picked up a set of winter tyres for my Cupra Ateca. Now, I have a “Limited Edition” version, and that comes with 20” rims as standard, and the only tyre pressure information provided on the door pillar relates to 20” tyres 42/39psi unladen.

The winter wheels and tyres I have acquired are 19” (yes, a 19” rim does clear the Brembo brakes) the tyre being 235/40/19 - and off an Ateca (that tyre size is one that can be fitted to the 2.0 TSi 4-Drive variant as standard).

My question is, what would the recommended pressures be for 235/40/19 tyres? The handbook, of course, just says “look at the door pillar”.

And yes, I checked with my insurers that they would allow fitting appropriate winter tyres when I took out the policy.

I have a standard 2019 Cupra Ateca 2.0 Tsi 4 drive, but mine has 245/40/19 tyres. So I can’t help I’m afraid, but for what it’s worth I have attached the door label tyre pressure for mine.

 

[rafletcher]

Well, thank you, and that’s interesting - the pressures you have are identical to those stated on mine for the 245/35/20 tyres! And not at all like the ones I’ve been able to find online. I wish I understood the hyroglyph about lower temps though, and the use of the ’i’ symbol. Ah, apparently the ‘i’ pressure figures (for medium load) can be used ”to increase driving comfort” at the expense of increased consumption, so that’s one mystery solved. And further reading of the manual (who knew? ) reveals the thermometer symbol is nothing to do with winter pressures, it just means check pressures when the tyres are cold. So, really, tyre pressures don’t seem to be that critical, so I’ll probably go with the comfort pressures and see how it feels.

Oh, and the handbook makes no reference to using different tyre pressures for winter tyres.

 

[RUM4MO]

I'm guessing that you have chosen 235 over 245 as that makes more sense as a winter tyre.
I noticed that when I first looked for winter tyre sizes for my S4 when I bought it, 235 was the width of tyre that Audi dealers held kits of winter wheels in, and so narrower rims than I was planning in using as I bought a used set of Audi A4 summer wheels - and if I had fitted 235 section tyres to them I would have been approaching the lower limit of tyre width relative to wheel rim width. So I opted for buying and fitting 245 which was the 18" factory wheel size option width for these cars.
My wife's 2015 Polo 1.2TSI came new with 16" with 215 tyres, the 15" tyre option is a 185, so I just went for that instead of going for a suitable compromise of 195. I worked out that if I was going to swop wheels summer/winter on that Polo, I might as well fit the width of winter tyre that gives the better grip under adverse conditions as it is only a 2 wheel drive car - I've been using Michelin winter tyres for almost 20 years.

Edit:- my older daughter uses "-1" " winter alloys, I tried to guide her and her partner on wheel rim width to be used tyre width - and I failed, so her winter wheels or wider than optimal for the tyre size that SEAT Leon uses with that size of tyre from factory, result of that, and maybe also due to wheel design, is, even although the winter tyres have a protection rib on them, when you stack the winter wheels on top of each other, there is alloy to alloy contact and I as with all of my wheels, tyre to tyre contact - so that means no rim protection is being offered - and it shows!

 

[rafletcher]

I bought some (Audi) 19” 8j rims for winter use, and the “ideal” tyre width (as found online) is 235. As it happens someone on here was selling his winter tyres - Michelin Alpin - as he‘d sold his Ateca, and they were 235’s, but yes, I usually go down 1 step in width and rim size, and up in profile for winter wheels and tyres. These are slightly smaller diameter so actual speed will be less than indicated speed, which also suits me in winter. I did check the Michelin site, and they state a 235/40 can be run on rim widths of 8-9.5”.

 

[RUM4MO]

That is a bit strange as Audi supply a 7.5" rim with their 235 wide winter tyres on 18" alloys, my S4 Audi 7 double spoke alloys as standard fit are 8.5" rim with 255 wide summer tyres. As I had bought Audi A4 18" 5 spoke alloys that have 8" rims, I found that I really needed to fit 245 wide winter wheels as that is the size that these alloys normally got fitted with.

I used to have a list of rim width V tyre width ranges - I found it online probably on an alloy wheel supplier's website and the sizes I've listed above ended up being right in the middle of the ranges for 7.5, 8.0 and 8.5 rims, so from that, if it is true, and VW Group seem to adhere to that plan, I think that your 8.5" rims are outside the technical recommendations for that tyre width, maybe check again online to see if what you are doing is okay as insurance companies usually require that you only fit recommended rims with associated recommended tyre sizes - or you could find that you will lose cover.

Edit:- I've looked online, and the first two guides I found do not tie in with the sizes that VW Group and some others I've checked with, they seem to be 0.5" out, even worse when including in the search the aspect ratio, so I can't work out what is going on there, I still can't find my original guide that conveniently ties in with how VW Group size things from factory fitted tyres and wheels.

 

[rafletcher]

Well I‘m using 8j for the 235 winter, not 8.5j . Just checked an the OEM 20’s are also 8j, with 245 tyres.

I found this: https://www.tyres-pneus-online.co.uk/tyre-equivalence-advice.html

 

[Bahnstormer_vRS]

So, today I picked up a set of winter tyres for my Cupra Ateca. Now, I have a “Limited Edition” version, and that comes with 20” rims as standard, and the only tyre pressure information provided on the door pillar relates to 20” tyres 42/39psi unladen.

The winter wheels and tyres I have acquired are 19” (yes, a 19” rim does clear the Brembo brakes) the tyre being 235/40/19 - and off an Ateca (that tyre size is one that can be fitted to the 2.0 TSi 4-Drive variant as standard).

My question is, what would the recommended pressures be for 235/40/19 tyres? The handbook, of course, just says “look at the door pillar”.

And yes, I checked with my insurers that they would allow fitting appropriate winter tyres when I took out the policy.

The best answer I am able to offer, from the door pillar label of my Cupra Ateca, is F 2.9bar R 2.7bar for the standard 245/40 19 tyres; with the subsequent caveat of the recommended +0.1 bar for Winter tyres.

To put this in context, having just been through the process myself of organising a set of Winter wheels/tyre, one piece of information I worked out is that the Cupra Ateca used one tyre size larger than the regular Atecas; rim sizes being equal i.e. you've got 235/40 19s from a 2.0L TSI whereas the Cupra uses 245/40 19.

As a 'soon to be (now am) Cupra Ateca owner' and doing my research on this subject, Google lead me to the earlier Wheels and (Winter) tyres thread on here; where several forum members reported using 215/50 18s from a regular Ateca on their Cupra, whereas a 225/50 18 is a closer match for rolling radius for the OE 245/40 19s - if that makes sense. A caveat on this is that 225/50 18s need a 7.5J or 8J rim, but the SEAT 18" rims are only 7J

I considered fitting 245/40 19 Winter tyres to the OE rims, with the view of getting an alternate set of 19s for summer use, but ruled this out on cost and not feeling comfortable with the wide 245s.

Ultimately, I opted to use a set of 7.5J x 18 ET37 rims I had on my previous car (Skoda Yeti 'vRS'), refurbished in Anthracite and fitted with 225/50 18 Continental TS850P Winter Tyres. The slightly wider offset resulting in the outer face of the wheel/tyres being in the same position +/- 1mm as the OE 19s, thus preserving the purposeful visual stance of the Cupra.


Coming back to tyre pressures.

I initially set my Winters to the OE summer pressures of F 2.9bar R 2.7bar (as above) but the handling just felt a tad squishy with these, which may have been due to the pressures or it may have been the taller Winter tyres.

However, last Friday, I got the tyres purged and reinflated with Nitrogen (as I like to do and wasn't able to do initially) and set at F 3.0bar R 2.8bar. The difference is noticeable with most of the tautness of handling returning. Result.


Guy

 

[Bahnstormer_vRS]

PS> I found, and have used in the past, the following links / websites useful in comparing / calculating wheel & tyre sizes;-

https://alloywheels.com/tyreCalculator

https://alloywheels.com/width-offset-calculator


Guy

 

[Glosphil]

I have 80% nitrogen in my tyres; that is atmospheric air. According to Michelin & Continental filling road tyres with nitrogen is pointless.

 

[Bahnstormer_vRS]

^^^^ 'tis true Phil.

Nevertheless, I have used Nitrogen in my tyres for 15+ years and like that, over time, they maintain a constant pressure and that the pressures do not vary significantly in use.

Guy

Sent from my XQ-BQ52 using Tapatalk

 

[rafletcher]

Thanks for the input all. The reason I’m fitting 19” rims is because the Limited Edition has the Brembo brakes as standard, and 18” rims don’t have the necessary clearance - otherwise I’d have fitted that size. And the reason I’m fitting 235’s is that a former Ateca owner had a set of Michelin Alpin 5 tyres with 7mm of tread on that he was selling (normally I’d go for a mid-range winter tyre like Nokian). I’ve not found anything from tyre manufacturers about increasing pressure in like for like sized tyres for winters.

For fitting comparison I used to use willtheyfit.com, but it seems to be down at the moment.

I‘ve also used https://www.wheel-size.com/calc/

 

[rafletcher]

Well I finally fitted the winter wheels and tyres at the weeken. Set at 39/36psi. My goodness, what a change to the handling from the factory fit Perelli 35 profile summers at 42/39! Obviously a softer and quieter ride, which I expected, but the loss of sharpness in braking wasn't. Perhaps I'll pop the pressures up a bit and see if that helps.