Tyres!,

[Welshquattro]

Need two tyres on my quattro which has 225/40-18's on at the moment,was wondering if I could fit 235/40-18's on just the two wheels for now until I save up for the other two. Was thinking of putting them on the back of the car but as it's a quattro will this damage it? Wheels are 8x18's. Thanks.

 

[ruffrida]

It wont be good for the diff bud, or so i was lectured about at the weekend from me brother, as i was running me spare for a week, hold on you said 225 vs 235, wont make a difference at all i would of thought, as the rolling height is still the same 40!! just be very slightly wider !!

 

[swarcup]

Isn't the profile a percentage of the width of the tyre so a 40% profile on a 235 is slightly deeper that on a 225 thus creating a slightly different rolling radius. If they are going on the back they wont set the speedo wrong, but on the front could give you a slightly false speed reading, however i dought in this case it would make a lot of difference

 

[Icarus83]

Have a look at http://www.willtheyfit.com/index.php

Will give you the differences between the different sizes.

Tbh the tiny difference in size shouldn't give the diff much difference in loading, especially for what is theoretically a 10mm wider tread. I put some new alloys on my car last night and I put a 225 tyre up against a 235 and I couldn't see any difference as different manufacturers have varying degrees of accuracy when it comes to the widths.

Will upload a pic in a second to show you what I mean.

 

[BRILLO]

If they are going on the back they wont set the speedo wrong, but on the front could give you a slightly false speed reading, however i dought in this case it would make a lot of difference[/QUOTE]
Are they not 235/40/18 from the factory anyway so speedo will be correct.

 

[Icarus83]

This is what I found between a Pirelli 235 tyre at the top and a Michelin 225 at the bottom. as far as I could tell there was no difference in the tread'ed area of the tyre.

 

[Welshquattro]

Thanks guys. The car came with 235's on but I changed them for 225's as they were cheaper but have noticed the rims have suffered as they seem easier to hit. Was thinking of 235's again to try and see if the rims fair any better with them but after see Icarus83's pics above I might aswell get 225's.

 

[morrisonbrink]

Seems to be a lot of variation on what different makes call a 235. I have a pair of conti 235s on the back of mine which give a LOT more protection to my 18x8 rims than identically labelled 235 falkens at the front.

 

[quattrojames]

As mentioned the 40 profile is a percentage of the width, so a 225 will have a different rolling radius to a 235 tyre. The difference is obviously minimal taking into account manufacturing tolerances etc..... But, how many times will those wheels rotate over the life of a tyre?! That's minimal difference will soon add up, and at the risk of being paranoid it won't do your diff any favours. If it was me I'd revert back to 235 all round which is the standard A4 18" wheels tyre size. 225's are fitted to the A3's. You could sell your 255's on as part worms to make some money back maybe.

 

[Welshquattro]

Thanks james,had a feeling it might not be such a good idea to have to different sizes on the car! I'll get the 225's fitted on the front as they need doing and save for a full set of 235's.