[DannyD]

Hello all,

Apologies if this is posted somewhere else but I am very, very bad at using the search function o the forum.

My VW came with 275/45R20 with a set of 50$ street tires. I am looking to change to a set of 19" rims (or 18 if I can find any) and a set of tires with 55 profile (aspect ratio) or 60 if I can get 18" rims.
Using the scenario of 19" rims and a 55 tires:
Online calculators tell me that my current setup has an overall diameter of 756 mm and the new setup will have 774 mm (2.5% increase)

I went to my local tires shop and the guy had a small meltdown and said that this will make my car give a lot of error codes because the change in diameter will change the speed reading on the speed sensor.
I am not a specialist so I did not argue but I do remember that modern cars use the ABS sensors for speed detection and that as long as all your tires are the same size there would be no issues and the speed will show exactly the same. Is he correct? And if he is then can the sensors be recalibrated in any way to compensate?

 

[TommiT]

All that will happen is that your speedometer, which currently over-reads actual speed by a few kph, will be more accurate!

 

[2MUCKY]

Hello all,

Apologies if this is posted somewhere else but I am very, very bad at using the search function o the forum.

My VW came with 275/45R20 with a set of 50$ street tires. I am looking to change to a set of 19" rims (or 18 if I can find any) and a set of tires with 55 profile (aspect ratio) or 60 if I can get 18" rims.
Using the scenario of 19" rims and a 55 tires:
Online calculators tell me that my current setup has an overall diameter of 756 mm and the new setup will have 774 mm (2.5% increase)

I went to my local tires shop and the guy had a small meltdown and said that this will make my car give a lot of error codes because the change in diameter will change the speed reading on the speed sensor.
I am not a specialist so I did not argue but I do remember that modern cars use the ABS sensors for speed detection and that as long as all your tires are the same size there would be no issues and the speed will show exactly the same. Is he correct? And if he is then can the sensors be recalibrated in any way to compensate?

I change my 275/45/20 to 255/55/19 which have a slightly larger overall radius. No issues and no warning lights.
Just make sure all 4 tyres are the same and you will be sweet. VW sell the car with lots of different tyre options and sizes.
Your speedo "might" be slightly more accurate.

 

[DannyD]

I change my 275/45/20 to 255/55/19 which have a slightly larger overall radius. No issues and no warning lights.
Just make sure all 4 tyres are the same and you will be sweet. VW sell the car with lots of different tyre options and sizes.
Your speedo "might" be slightly more accurate.

Do you know the rim depth? Standard would be 9 and I found some that are 9.5 with offset 49.

 

[2MUCKY]

Do you know the rim depth? Standard would be 9 and I found some that are 9.5 with offset 49.

Sorry I don't. They are genuine VW wheels. I'm sure someone on here can identify them.

 

[chewblekka]

I went to my local tires shop and the guy had a small meltdown and said that this will make my car give a lot of error codes because the change in diameter will change the speed reading on the speed sensor.

Take your vehicle to someone who doesn’t smoke lots of crack cocaine.

If all 4 wheels are the same size/rolling diameter the speed sensors have no idea what size the wheels actually are. They simply read square waves created by the variable reluctance tone ring. If you could somehow fit 10” Daytons on your Touareg, or 30” Donks, your Touareg would have no idea.

There is an intentional offset in actual wheel speed and the displayed speedometer for legal reasons. This allows manufacturers to equip their vehicles with a range of wheel sizes (say 16”-20” ) and the speed will still be within a legal amount, and each specific trim won’t require specific coding.

 

[87vr6]

I went to my local tires shop and the guy had a small meltdown and said that this will make my car give a lot of error codes because the change in diameter will change the speed reading on the speed sensor.

FYI, the "correct" size for a T3 on 19s is 265/50/19.


So, I'm assuming you want to go to 275/55/19? You're going to gain 1.2" in overall diameter from your current 275/45/20 if so, and may run into clearance issues if you're not lifted at all. That's a 31" tire.

 

[TommiT]

31.5 inches is the maximum OD.

 

[DannyD]

I would like to go to 18"x9" to allow me to install 265/60R18 but I cannot find any rims in that size that are compatible.

So far, I have found a few but most of them come with a 38 to 40 offset and will cause my scrub to go positive with 15-18mm. I am not an engineer so I have no idea what that will cause....