I'm looking to replacing my current 21" stock to 20" stock XC90 wheels and tires. Do I need to go in to Volvo to update the firmware for the speedometer?
Changing 21" to 20" with Volvo's stock tire
hohohong
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Likely, yes. For sure going from 20" A/S to 22" Summer required an updated. This is the very first year out of 6+ years of ownership and swapping 20" -> 22" -> 20" ... where I was charged by the dealer for this software update. Sign of the times ....
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If outer diameter is the same then there's no need. Last year when I was in yellowstone I hit a pothole and blew one of my rims. Had the car towed to Underriner Volvo and all they had was a bent 20 inch wheel from a XC40 that they were throwing into trash bin. Since I really needed a wheel to get back to Seattle, I bought a brand new 20 inch tire (275) and they gave me that rim for free. Drove the car all the way back to Seattle without any issues. The car had brand new tires just mounted so thread wear was not an issue.
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As long as the tire width is 275mm (e.g. 275/40/21), you do not need to have the software update. You only need the software update if you're changing the width (e.g. the 19" wheels have a 255mm width, so changing to the 20" or 21" 275mm would require a change in software)
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This is incorrect, it is all about diameter. Width has nothing to do with it. Which is why most temporary spares are 125mm width.
take the width, multiply it by the aspect ratio percentage, so 275mm x .4 = 110mm sidewall. Then double that, convert to inches, 220mm = 8.67", plus the rim diameter 21, and you get a tire with diameter of dang near 30" in this case, more than 2" taller than stock 245/40/20 on my car.
And FWIW, on Tire Rack their factory sizes for a XC90 include these, all about the same diameter.
The relation of aspect ratio to the rim size keeps the same overall diameter despite keeping the same width.
Here is a online tire size calculator for those aren't feeling crunching the numbers and for easier comparison.
tiresize.com
It's interesting that 235/55R19 is about 1.7% smaller than 275/40R21 comparing to 0% for the 20s and 0.3% for the 22s. Not sure if software needed to be updated between the 19s and 21s. Would be nice to have some reference for the software/computer in these cars.
Tire Size Calculator
The best tire size calculator. Use our tire size calculator to find tire size specs and suggested tire sizes. Then check prices for all available tire sizes.
It's interesting that 235/55R19 is about 1.7% smaller than 275/40R21 comparing to 0% for the 20s and 0.3% for the 22s. Not sure if software needed to be updated between the 19s and 21s. Would be nice to have some reference for the software/computer in these cars.
‘19 t6 inscription silver/brown w/air, b&w, lux, polestar, 21’s, etc
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The software update for change in tire size (between factory or similar diameter sizes) is nonsense IMO. Yes our Volvo is probably the only car I’ve owned where the speedometer exactly matches the speed on GPS, so that might be why they “require” it. Kinda silly & unnecessary from a company that won’t even give tire pressure readings with direct tpms. Does it really matter if the speedometer is off 2% when switching tires? It’s never mattered in any of my other vehicles so I can’t see why it would matter here…all of those were at least 2% off between speedometer and gps from the factory.
It's possibly affecting the tire pressure calculation since there isn't a sensor to measure pressure. However, who knows how much that really affects the calculation.
Thank god that the volvo isn't my primary vehicle!
FWIW....I put 18” Steelies winter wheels and tires on past winter and got the closest match diameter to my stock 21” AS, and if I recall correctly the diameter was off by 2%. Never went to dealer for it to have speedo calibrated and never had any issues, am sure Speedo was off some but insignificant. Before getting in this Volvo drove BMW’s for over 20 yrs and all their speedometers are off some (lower by design) from the gps never causing any problems....
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The software (P/N 32270047) is specifically for changing from a 255mm tire to a 275mm tire and changes the steering angle parameters to prevent rubbing. I had a long discussion with the tech when going from the 19" to 21" wheels since the overall circumference was <1%, but had to do the software anyway because of this.
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Wow, that is REALLY odd, if so, sorry, I stand corrected. I never have heard of software limiting how far you can turn the steering wheel. I know they have sensors on steering angle, but not limiters.
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Any idea how much smaller width (235/55-19) would affect overall handling/braking/acceleration in the XC90?
I'm looking for more side-wall in a tire and the 19" tire, while not quite as much sidewall as I'd like, is close enough for me. But I'm curious what it would cost in terms of performance with the smaller width tire.
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Only a W.A.G. is none, unless on rain, then depending on tread depth. Could be better and/or worse all at once. With the XC90, just make sure load range is met.
265/50-19 could be a better choice if you are looking for more sidewall and be close to stock performance.
Additionally, 245/55-19s are closer match in terms of overall diameter to the 20s, 21s, and 22s. Not sure if how available 245/55-19s are though.
‘19 t6 inscription silver/brown w/air, b&w, lux, polestar, 21’s, etc
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Interesting…didn’t know about the width adjustment for steering. So in that case, would be best to have steering calibrated for wider tires, and suffer the tiny increase in turning radius of using narrower tires in winter, etc to avoid paying to recalibration each time
Best 19” tire size would 255/55/19 for load range and tire selection. Personally, I would (and likely will when 21’s wear out) go with a 20” wheel and 265/50/20 tires due to better selection and lower price than 275/45/20
Best 19” tire size would 255/55/19 for load range and tire selection. Personally, I would (and likely will when 21’s wear out) go with a 20” wheel and 265/50/20 tires due to better selection and lower price than 275/45/20
Is there any way the software can be updated without dealer involvement. I am trying to change my stock 22' to the spare 19' wheels and the local dealer (in Australia) needs $240 odd each time I move between wheel sizes. Seems too steep to me and I am trying to see I can have it done cheaper.
We have a trip down to Snowy Mountains in a week and was told my 22' may not do too well.
We have a trip down to Snowy Mountains in a week and was told my 22' may not do too well.
Correct me if I am wrong here but that SW mentioned is for going from small to larger to avoid rubbing, which will not be an issue when going smaller which is what this thread is really about.....
I was advised by our Volvo dealer it is needed both ways - 22' to 19' and back to 22 again.
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My 2¢ (I have a lot of them) don't rule out the possibility they are wrong.
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