Do Not Sell My Personal Information Jump to content


Is250 Wheels/tyres


Recommended Posts

I know that the rear wheels and tyres on the new IS are slightly different size to the front, compared to the old IS, so I have a question, how much difference does it make fitting new IS wheels and tyres to the old IS without changing the tyres over?

Link to comment
Share on other sites

what i'm asking is if I don't change the tyres (the wheels i've seen have tyres already fitted and are almost brand new) how far out will the speedo reading be?

Link to comment
Share on other sites

Rear wheels (including tyres) will have a 4.1% larger circumference and front wheels (including tyres) will have a 1.4% larger circumference.

i.e you will be travelling ~ 5% faster than what your speedo shows.

:offtopic: So the MK2 IS front wheels are bigger than the mk1 IS rear wheels :blink: . I remember my cousins M3 having rear wheels around 245/40 17. Wonder if the IS actually needs the width, as thats increasing rolling resistance a fair bit. Must be better for handling and braking as larger surface in contact with road, although wonder how they would react to potholes etc :yawn:

Link to comment
Share on other sites


This isnt a massive amount. Around 14mm difference in radius, bearing in mind there is a difference of 5mm with new tyres compared to tyres that are still within their legal limit.

Speed cameras allow for ~10% over the limit, hence 5% on your speedo would be fine, presuming your speedo isnt already out.

Link to comment
Share on other sites

the site I checked for fitment stated the speedo reading compared to actual speed needed to be within 2.5% so I don't really want to risk nearly 5% thanks for the help with my query, much appreciated

Link to comment
Share on other sites

the site I checked for fitment stated the speedo reading compared to actual speed needed to be within 2.5% so I don't really want to risk nearly 5% thanks for the help with my query, much appreciated

1. The speedo is out by 10% anyway right?When my speedo reads 80 MPH my GPS says 71MPH

2.It will keep your miles down :o :winky:

Link to comment
Share on other sites

I saw my car there :D

At the rear, the 17 and 18 inch standard wheels are offset 50.

You can put 235/45R17 or 235/40R18 (like mine) on without having to roll the arches. Even with 30mm lowered suspension. The speedo will be very close to stock.

If you want to use the IS250 tyres, which are 245/45R17 or 255/40R18 you'll need to roll/shave the rear arches slightly.

On the fronts, the 225 tyres will fit straight on, in some cases you'll have to stretch the plastic wheel well liners ab tiny bit (blowdryer).

Cheers,

RX-Men-8

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share



×
×
  • Create New...