Feels like taller gearing after fitting 17" wheels

[tig125tsi]

Hi guys,

I have a strange problem. I just upgraded my wheels from the stock 16s to 235/55/17 tiguan wheels (boston style). The tyres are pretty much brand new. However since changing the wheels, it felt like the car has less torque under 2000rpm. By the way, mine is a 6 speed manual 125TSI 2010 model.

I used to be able to go into 6th gear doing 60kph and the car would rev about 1400rpm and not struggle. Now going into 6th gear requires minimum 70kph and it is doing 1400rpm, same as before.

It feels like changing the wheels to 17" made the gearing taller.

Am i dreaming this or is this possible?

regards,

Frank

[DoggieHowser]

What was the original rim and tyre size?

You can compare rolling diameters with tools online.

It's more likely you are feeling the added rolling weight of bigger/heavier/wider tyres and rims.

[HaydEn]

Bigger wheels/tyres will have this effect.

[tig125tsi]

What was the original rim and tyre size?

You can compare rolling diameters with tools online.

It's more likely you are feeling the added rolling weight of bigger/heavier/wider tyres and rims.

The originals were the factory 16" wheels, i think they were 215/65/16. Okay i will find an online tool to compare the difference. The 17" did feel slightly bigger when i was putting them on the car. I remember when i took out one of the wheels from the car, i had to jack it up further to fit 17" one.

[tig125tsi]

In saying that, would my speedo not be accurate anymore? I do remember reading somewhere that the speedo gets its calculation from the gearbox, rather than the tyres. Is that correct?

[DoggieHowser]

The internal speedo is usually off anyway. I usually use the GPS. I've driven on some roads where they ask you to check your speed and displays them on a big board as you drive past and the GPS is usually spot on (provided you are at a constant speed).

To check the difference in tires
Tire Size Calculator - tire & wheel plus sizing

It shows a 0.6% increase in size.

I usually try not to increase the rim size unless I am going for a good lightweight design that compensates for the increase in size.

[Hillbilly]

Use this it will even tell you what the alteration to your speedo is

Custom rims, wheel tire packages for your ride - RIMSnTIRES.com


There is also a legal amount that you are allowed to increase diameter by.

In NSW I think its only about 25mm similar in QLD.

Perhaps you should check

A stock speedo is legally allowed to be up to 10% fast < >4% but may not read slow at all

MY Polo is 7kph fast at 100kph and the Passat is 3 fast.

It would take wheels 40mm bigger to bring the Polo back to correct but would be illegal and would put the gearing up too far as well.

[Diesel_vert]

215/65 R16 and 235/55 R17 are both factory fitments.

The rolling circumference (CR) of a 215/65 R16 and 235/55 R17 tyre is 2092 mm and 2105 mm respectively.

I just upgraded my wheels from the stock 16s to 235/55/17 tiguan wheels (boston style).

However since changing the wheels, it felt like the car has less torque under 2000rpm.

I used to be able to go into 6th gear doing 60kph and the car would rev about 1400rpm and not struggle. Now going into 6th gear requires minimum 70kph and it is doing 1400rpm, same as before.

It feels like changing the wheels to 17" made the gearing taller...

Am i dreaming this or is this possible?

Don't worry. As everyone has pointed out, it's normal.

If the bigger wheels and tyres are heavier (and they usually are), naturally they will sap a little bit of power.

If the CR of the tyre is bigger (and it usually is), this will have the effect of lengthening the gears (as you've already pointed out) which further exacerbates that feel.

A tyre with a bigger CR will also make the speedometer less overestimate the vehicle's speed.

[tig125tsi]

thanks for your replies guys.

[Hillbilly]

215/65 R16 and 235/55 R17 are both factory fitments.


A tyre with a bigger CR will also make the speedometer less underestimate the vehicle's speed.

???? It will actually bring a speedo to read more correct I worked out my Polo which is 7kph optimistic would come correct with 40mm larger diameter tyres which unfortunately would seriously over gear it and be outside legal size increases..

All speedos must read, if not correct must over estimate the true speed.

They cannot legally UNDERESTIMATE it EG read 97 when doing 100