Different tire sizes

[Colin Macfarlane]

Hi, I am the new owner of a 2023 PHEV. Had it for a week (no gas yet - 200 kms) and still going through the manual.
One of the purchase items is winter tires and rims, as the first owner just had all-seasons (not really a good idea in Nova Scotia winters). The SEL came with 20-inch rims/tires, but I ordered 18-inch rims and spent more on the tire instead (Michelins). Yeah 18s are fine, especially as most of the long haul driving to relatives is in the summer when 20-inch rims are cool.
HOWEVER, now I get into the manual, and the Caution on 10-27 says don't mix tire sizes. I assume they consider users know not to put differing tires on at the same time, so this means don't do what I am trying to do (tires are not available yet, so I can change to 20s - at a price). The caution says the TPMS will be set to the original tire values, and will not accurately monitor something different.
My question is: the local dealer will be changing the tires as required, so can they not adjust the TPMS each time I change the tire size?

 

[DaveL59]

As with most vehicles, I expect that's more about mixing sizes on the same axle, but also because of the EV system, no differences front-to-back also. So all 20's or all 18's would be fine.

If your new 18's have TPMS sensors fitted, you can have them programmed in as set 2 to the car's TPMS monitor IIRC and then switch between sets when you switch from summer to winters. Others may be able to confirm that.

 

[greendwarf]

As with most vehicles, I expect that's more about mixing sizes on the same axle, but also because of the EV system, no differences front-to-back also. So all 20's or all 18's would be fine.

If your new 18's have TPMS sensors fitted, you can have them programmed in as set 2 to the car's TPMS monitor IIRC and then switch between sets when you switch from summer to winters. Others may be able to confirm that.

Yep, that's the way once the dealer has programmed in the second set of sensors. I did originally just change the tyres over twice a year at first but bought a second set of rims some years ago through this forum. Since then I have swapped the wheels & tyres over myself and it is quite simple switching between the sensor settings (see manual).

Having two sets of tyres does mean they last longer and you always have a "spare" available in an emergency but last winter I decided to go just for a set of Continental All Season Contacts rather than buy 2 new sets after they rapidly wore due to some misalignment issues. So now I still have 2 sets of wheels but only the one set of tyres!

PS. Storage is a bit of a bind with a second set of wheels & tyres!
PPS. I have in 10 years only once used the winter tyres extra grip once in the Alps and that was soon after I got them

 

[BobK]

Hi, I am the new owner of a 2023 PHEV. Had it for a week (no gas yet - 200 kms) and still going through the manual.
One of the purchase items is winter tires and rims, as the first owner just had all-seasons (not really a good idea in Nova Scotia winters). The SEL came with 20-inch rims/tires, but I ordered 18-inch rims and spent more on the tire instead (Michelins). Yeah 18s are fine, especially as most of the long haul driving to relatives is in the summer when 20-inch rims are cool.
HOWEVER, now I get into the manual, and the Caution on 10-27 says don't mix tire sizes. I assume they consider users know not to put differing tires on at the same time, so this means don't do what I am trying to do (tires are not available yet, so I can change to 20s - at a price). The caution says the TPMS will be set to the original tire values, and will not accurately monitor something different.
My question is: the local dealer will be changing the tires as required, so can they not adjust the TPMS each time I change the tire size?

I also live in Nova Scotia, have a 2023 PHEV with 20" rims and I have Michelin winter tires on 18" rims. I bought the tires from the dealer (price was competitive) and they assured me the smaller rim size would not be an issue with the odometer etc. Just now I went outside and measured the two sets of tires. Even though the Michelins are on 18" rims, the side walls are much deeper (4.5" from the outside of the 18" rim vs 3" from the outside of the 20" rim with my summer tires). The result is the diameter appears to be pretty much the same at 28 to 28.5 " (hard to be precise with the rounding of the tires), which would mean the car probably wouldn't see a difference. The reason the numbers don't quite add up is the standard rim diameter appears to be measured as an inside diameter, but the sidewall measurement I made was from the furthest edge of the rim to the tread.

 

[Colin Macfarlane]

The young lad who I was dealing with when this 2023 appeared had been a tire changer for 9 mos before becoming a salesman. He liked the 18s for the reason you mentioned, which made it actually a more rugged tire. I have asked about the cost of 20 inch rims and tires vs 18, just because another poster did mention that wrecking one rim and having 4 spares close by is kinda useful.

 

[phevGoBzzzzzz]

The 2023+ models don't need tpms programming.

Just swap the wheels and after a few minutes of driving the new tires will automatically pair to the car.

 

[chezz]

I also live in Nova Scotia, have a 2023 PHEV with 20" rims and I have Michelin winter tires on 18" rims. I bought the tires from the dealer (price was competitive) and they assured me the smaller rim size would not be an issue with the odometer etc. Just now I went outside and measured the two sets of tires. Even though the Michelins are on 18" rims, the side walls are much deeper (4.5" from the outside of the 18" rim vs 3" from the outside of the 20" rim with my summer tires). The result is the diameter appears to be pretty much the same at 28 to 28.5 " (hard to be precise with the rounding of the tires), which would mean the car probably wouldn't see a difference. The reason the numbers don't quite add up is the standard rim diameter appears to be measured as an inside diameter, but the sidewall measurement I made was from the furthest edge of the rim to the tread.

On my 2019 PHEV I have the 18's standard for summer and 16's for winter, I found a website to calculate the closest size for 16 rims required to match the standard supplied tires on the 18's

 

[ckracer76]

After trying summer, all-season and winter tyres over the years, I found a permanent solution for my Outlander PHEV and fitted mild all-terrain tyres. My local Mitsubishi dealer recommended same size so I chose General Grabber AT3 all-terrain tyres that have so far proved highly effective.

I had initial reservations as I don’t go far off-road and the Outlander PHEV is no mud plugger. All-terrain tyre specs would have you believe D for wet and D for mpg but this couldn’t be further from the truth in my experience to date. After seeing many different brands of all-terrain tyres fitted to SUV’s, pick-ups, vans and even sport cars I took the plunge. I can see why all-terrain tyres are fitted to the Ford Raptor, Porsche 911 Dakar and Lamborghini Sterrato.

They are also winter rated and marked M+S and carry the 3PMSF mountain snowflake to be complaint in regions that require winter tyres.

My tyres were also 11mm tread depth from new which is a bonus I wasn’t expecting. Most tyres are 8mm I’m told.

The only downside I can report is a little bit more tyre buzz on smooth tarmac with windows down.

Handling, grip and wet weather performance on tarmac roads has been exemplary and off-road ability has been excellent on some mountain tracks. muddy paddock and grassy fields here in Wales.

Highly recommended.

 

[BobK]

I suspect in Wales your choice of tires is ideal for your conditions. Here in Canada the temperature gets a lot colder and we have many months of snow and ice. True winter tires are a softer rubber than other tires, which gives a better grip on very cold tarmac, but wears excessively above 7C. They are also covered in sipes, which are thin horizontal cuts in the tire rubber that deform when stopping or accelerating to provide a sharp edge to dig into packed snow and ice. Anyone that is serious about road safety in this climate has two sets of tires. Here is a good explanation: https://www.tirebuyer.com/education/all-terrain-vs-winter-tires

 

[greendwarf]

I suspect in Wales your choice of tires is ideal for your conditions. Here in Canada the temperature gets a lot colder and we have many months of snow and ice. True winter tires are a softer rubber than other tires, which gives a better grip on very cold tarmac, but wears excessively above 7C. They are also covered in sipes, which are thin horizontal cuts in the tire rubber that deform when stopping or accelerating to provide a sharp edge to dig into packed snow and ice. Anyone that is serious about road safety in this climate has two sets of tires. Here is a good explanation: https://www.tirebuyer.com/education/all-terrain-vs-winter-tires

Although I only ever used the snow & ice performance of my winters once, to be able to drive smoothly up a long hill on an untreated French Autoroute past all the other stranded local vehicles, means they were worth every penny!

 

[mellobob]

Although I only ever used the snow & ice performance of my winters once, to be able to drive smoothly up a long hill on an untreated French Autoroute past all the other stranded local vehicles, means they were worth every penny!

I live in southern British Columbia in the mountains. I would never do a winter without snow tires. Matter of fact, it is illegal to drive in the winter without "snowflake" tires which include so-called all season tires (but it shouldn't).

 

[ckracer76]

Here in Wales we don’t have any seasonal tyre laws like in Scandinavia or Germany and most people aren’t even aware of the different tyres available.

My basic understanding of tyre (tire) rubber compounds is;

Summer (Hard)
All-season (Medium)
All-terrain (Medium)
Mud-terrain (Soft)
Winter (Soft)
Ice studded (Soft) illegal in UK.

Although we are allowed to fit snowchains to any tyre.

I imagine rubber compounds varies from manufacturer to manufacturer and maybe even regional differences & sizes.

The motorsport divisions and fraternity seem more geared up to discuss tyre and brake compounds than regular motorists.

I’m told all-season is popular in North America.

Does US and Canada have seasonal law for tyres? The UK grinds to a halt the minute it snows which is hilarious and embarrassing.

 

[DaveL59]

In fact, snow/winter rated tyres are not so much 'soft' but a different compound that remains more pliable below 7C where regular summer compounds don't and hence have poor grip at low temp regardless if they are 'softer'.

On the Alfa v6 I used to have I ran winter tyres from Oct-mar and in this hilly area they made a huge difference pulling away into traffic etc. I used to have to run cross country lanes on part of the journey down south where I was working back then and again grip in the tight twisties was excellent where I'm sure the summer tyres would've struggled.

As noted by others tho, winters do wear faster once temps hit 10C or higher and they also tend to be less good once 3 years or older, grip-wise. Worth the investment IMHO.

 

[mellobob]

Here in Wales we don’t have any seasonal tyre laws like in Scandinavia or Germany and most people aren’t even aware of the different tyres available.

My basic understanding of tyre (tire) rubber compounds is;

Summer (Hard)
All-season (Medium)
All-terrain (Medium)
Mud-terrain (Soft)
Winter (Soft)
Ice studded (Soft) illegal in UK.

Although we are allowed to fit snowchains to any tyre.

I imagine rubber compounds varies from manufacturer to manufacturer and maybe even regional differences & sizes.

The motorsport divisions and fraternity seem more geared up to discuss tyre and brake compounds than regular motorists.

I’m told all-season is popular in North America.

Does US and Canada have seasonal law for tyres? The UK grinds to a halt the minute it snows which is hilarious and embarrassing.

Laws as to season laws will vary from area to area. In British Columbia "snowflake" tires (winter or all-season) are required. Remember, Canada and US are both vast areas and have tremendous ranges of climate.

 

[ckracer76]

I have just been told by a colleague that grip in cold weather conditions is actually to do with heat generation. Soft tyres stay pliable in cold temps. Apparently the sipes in winter/snow tyres generate more heat?

This must be why I see race teams using tyre warmers before a race. So they have an immediate grip advantage from starting.