I changed to 18” wheels with Pirelli AS. First of all, the tires are much cheaper. Second, the ride is amazing, fuel consumption improves and easier on your suspension because of the unsprung weight. I didn’t calibrate anything on my speedometer because I never even look at it. I just fly with the flow.

 

how much do you think fuel economy improves? thinking of going from 20s to 19s on my T8 when I need new tires

 

Nothing will happen and frankly don’t even need to have the car recalibrated. Only downside is by putting narrower tires with higher offset wheels, the tires will sit inboard and likely look a little funny with the fender extensions.

 

also interested in downsizing to 19 or 18 if possible. mine came with 21 as default as well and it's fine but i'm more of a functionality over looks guy.

 

Yes. My 2021 came with 20” and now I’m riding on 18”. Very comfortable and affordable ride. I paid $750 for the Pirellis vs $2,000 in the size of 20”.

 

Yes, I bought the wheels here from a forum member. Ordered the tires from Tire Rack and got them mounted and balanced at the dealership.

 

kind of a bummer that a lot of the dealer ordered vehicles come with big rims even in an area infamous for bad road surface and debris. i'll be on lookout for smaller wheels

 

Pros

-Cheaper tires (21” is not a very common wheel size most use 20 or 22 which makes finding good tires cheap really difficult)

-You can go for a higher profile tire which will significantly increase the ride quality.

-Protect your wheels from curbs with a thicker sidewall

- Better off-road handling

Cons

-Looks worse IMO. HOWEVER function over fashion is definitely worth it.

- Less steering feel/responsiveness. Larger wheels tend to be more nimble and responsive to the road surface

- Better fuel economy due to the less rolling resistance as your wheels becoming lighter therefore less energy from the engine is required to move them.

All in all smaller wheels are more economical and sensible however larger wheels are more sporty and fashionable.

 

Very good summary. When I put on the 18” wheels my wife told me that the whole vehicle looks weird and smaller etc. I opened the passenger door for her to get in and we went for a ride. Asked her: “what about now? How does it look?” She said that she can’t tell because she’s inside the car. So that’s the point. 98% of the time I’m sitting inside. 2% walking to/from the vehicle. Who cares what other people think about my car? The previous generation XC90 came with 17” wheels and people loved it.

 

Ummm... you definitely do need to have your speedometer recalibrated. It's the same system that's used to calculate the vehicle's overall mileage (odometer).

With the wrong wheel sizes your service intervals will be off. You may end up selling your car for less than its actual value because your miles will be overinflated. Either that or you could end up with a very unhappy future owner who (depending on your view of humanity) will try to sue you for selling them a car with underreported mileage. Not saying that something so dire WILL happen, but why put yourself at risk? Even if the car drives fine ... it's a kettle of fish and a simple step that you shouldn't skip... also known as common sense.

 

Ummm... you definitely do need to have your speedometer recalibrated. It's the same system that's used to calculate the vehicle's overall mileage (odometer).

With the wrong wheel sizes your service intervals will be off. You may end up selling your car for less than its actual value because your miles will be overinflated. Either that or you could end up with a very unhappy future owner who (depending on your view of humanity) will try to sue you for selling them a car with underreported mileage. Not saying that something so dire WILL happen, but why put yourself at risk? Even if the car drives fine ... it's a kettle of fish and a simple step that you shouldn't skip... also known as common sense.

😂😂😂 Good luck with that lawsuit. Especially when he switches to smaller tire which results “slightly” higher mileage rather than lower. I can take that risk.

 

😂 no you don’t, unless a 1.5%-2% change really bothers you. Most vehicles have 2-4% speedo error right off the showroom floor. Worried your 10k mile service intervals are 150 miles off? Then yes…by all means pay the dealer a couple hundred bucks to recalibrate it so you can sleep better

 

do we know what kind of wheel/tire configuration the EPA fuel efficiency estimates used when generated?

 

Check your tire and wheel sizes using one of the online tire size comparison calculators and you'll be able to see if you need to recalibrate anything.

Smaller wheel with a higher profile tire looks better on an SUV IMO. Big rims and low profile tires look impractical and out of place. But then again, I don't like huge wheels on my S60 either.

 

There is a VIDA software that should be applied to identify the wheels installed so that all systems are aware of the change. You are changing rolling resistance, stopping traction and wheel circumference. Personally, I prefer all of the systems to be aware of the installed hardware so they can make accurate calculations in a safety related event. And yes, your speedo will be off by a good bit as the replacement wheels are 4.9% smaller in circumference.

When the car says its going 50mph it will actually be going 46.7 mph. You will needlessly run up your odometer and this is why your MPG is so much higher on the display. It is not that might higher in reality. The car just thinks its gone farther than it has.

Also the wheel offset if wrong and it will look a bit off. You can add 15mm spacers to make it look closer to stock.

 

I don’t think that switching from 21 to 19 requires any programming. Do you think in Europe people do it twice a year when switching between winter and summer tires? And the 21” tires are 275/40r21 not 275/45r21 what you used in the calculator. The difference is 50 mph vs 49.2 mph.

 

You could put even smaller or larger tires on the car and it will drive down the road. But the speedometer will be off and the ABS system baseline configuration will be incorrect. It will drive though. Unless the circumference of the alternative wheels + tires combination is maintained the speedo will be off. There is a reason tire and wheel size is a configuration option in the CEM.

Just because people swap wheels doesn't mean its a good idea, in a modern car, to not make the associated changes in the car configuration. Like I said, you will be running up your odometer because the car will be driving less miles than the odometer says. Putting more miles on the odometer, than actually driven, would be the number one reason I was make the software switch as it impacts the perceived value of the car. I guess you could try explaining to the next buyer, or the dealer (when you need warranty work), that the odometer is inflated artificially 4.9% because the car is running a non standard wheel + tire configuration and that there are actually less miles than the odometer says.

 

Please read again my previous post. The difference is 0.8 mph at 50mph.

 

Thank you, yes, I see the error now. I was going off of the OP's original post which stated 275/45R21. The OE 21" size is indeed 275/40R21. Here is the updated offsets. The 19" wheel combination is only 1.7% smaller in circumference. Yes, it is very small and I would not be worried about the odometer. I would still be concerned with the safety systems working optimally with the different tire patch size.

My personal story, my 2016 came with 22" wheels. I had the XC90 19"s sitting around which I planned to put on my P3 XC60. I had a 8000+mile rode trip planned and decided to swap the 19" for the road trip. I already had a VIDA sub going for unrelated work so applied the config change for the road trip. When I returned I decided to go with 20" wheels going forward. After installing those I once again updated in VIDA. Maybe cost me $125 between the sub price and the software package (maybe $50). Anyways, piece of mind. I want my Volvo to be as safe as can be. Volvo states that the wheel change impacts Speedometer, Steering gear and tire dimensions.

I am just trying to provide as much information as possible about my understanding of how the Volvo CEM configuration uses tire size information and why I think it is important to update it.

 

Lmao you give the car too much credit. What about friction coefficient on running a 200tw summer tire vs a 600 TW all season? How does the programming compensate for that? What about sidewall plies to determine deflection? The only real advantage I’ve read about on this forum is when running a narrower tire, the program allows more steering lock. But then again haven’t heard of anyone going from a narrower setup to wider (oem sizes) without programming that had trouble with tire rubbing.

It does affect those three things, but very minimally. Whatever helps you sleep better I suppose…

 

Everyone has their own risk tolerance. For me, since I didn't design the vehicle, I just drive it, I prefer to have the car configured per the manufacturers specifications especially if it only costs me a few bucks to make the change....lol

 

As for programming the car when wheel sizes change, I've read that it isn't just about correcting speedometer for diameter differences, but also, it allows for max steering range since larger wheels have more "tuck" room and can typically allow more tigher turns. So the smaller wheels are limited in steering angle.
BUT, that is only what I've read, I really don't know for sure.

 

I asked Volvo Belgium about it.
The answer was that the car needs to know the wheel/tyre setup since it is a parameter in
some safety related features such as Roll Stabilty Control and Run-Off Road Mtigation.
The movement of the car will be different if the wheel/tyre setup is changed and the action(s)
the safety systems take to keep the car on the road depend (among other things) on knowing
the wheel/tyre setup.

 

I asked Volvo Belgium about it.
The answer was that the car needs to know the wheel/tyre setup since it is a parameter in
some safety related features such as Roll Stabilty Control and Run-Off Road Mtigation.
The movement of the car will be different if the wheel/tyre setup is changed and the action(s)
the safety systems take to keep the car on the road depend (among other things) on knowing
the wheel/tyre setup.

That’s why I turn off all the safety systems. 😂 The car doesn’t have to no sh**t.

 

Additional information, here are the software part numbers to update the wheel configuration. MSRP is $48.72
32270046 - 235/55R19
32270047 - 275/45R20
32270048 - 275/40R21
32270049 - 275/35R22

 

This is purely anecdotal but I can tell you that my '22 T5 AWD gets 33-34 mpg HWY (midwest driving) consistently @ 75 mph and I have the 235/55/19 Continentals. I have exceeded 600 miles on one tankful. I specifically chose that size for: 1) Lower tire replacement costs 2) Availability of choices in that size (especially if needing to replace a tire while on a trip) and 3) Potential lower rolling resistance. I said "potential" because each tire is different so there's no guarantee that a 235/55/19 will have less rolling resistance than a 275/45/20.

 

How much savings on fuel did you notice running on 19 inch wheels