[MEGA]

^ this.

Either way 265/35 is 1% larger rolling diameter than 255/35 So doing the same front and back means 2% out (2.2% out or something from the calculation I did earler)

But its not major. It wouldn't put me off the change. And its pos, not neg. Going neg is worse as then your doing 60 and think your doing 56, etc. Not good for the speed cameras !!

Anyway. There you go.

[TMP]

Originally Posted by milesr3

Absolutely. But the advice from Falken Technical (actually handled by Micheldever) is to run them at the factory recommended pressures and not increase them for non-RFTs.

AIUI tyre pressure is a primarily determined by axle weight rather than tyre construction.

...and 6psi is a very big increase. I'd be worried about uneven tyre wear.

Agreed - you may well get more centre tread wear, but it will reduce sidewise travel on the sidewall ....

At least VRed's recommend an increase in pressure (seems most peeps who go down non-RFT route end up increase pressure to stiffen the side walls)

[toxicnerve]

Originally Posted by Yahoo

The second number (the profile / height of the tyre) is not an absolute measurement - it is relative to the first number ie the width of the tyre.

Ahhhh, this clears it up.

[HighlandPete]

Originally Posted by toxicnerve

Ahhhh, this clears it up.

Just remember it is an 'aspect ratio'.

HighlandPete

[toxicnerve]

Originally Posted by HighlandPete

Just remember it is an 'aspect ratio'. 255 X 35 etc.

HighlandPete

Riiiiiiiiiiiight. This I didnt know, I thought it was an absolute measurement, I'll get my coat now

[doughboy]

Originally Posted by MEGA

But its not major. It wouldn't put me off the change. And its pos, not neg. Going neg is worse as then your doing 60 and think your doing 56, etc. Not good for the speed cameras !!

Wrong way round mate.

Smaller rolling radius makes your speedo overread, i.e read 65 when you're doing 60.

[jke11y]

4 new FK452s fitted today - add in usual chat about feels like a newcar / why didnt I do this months ago.

Two of the RFTs that came off had visible cracking / delamination where the tread blocks met the sidewalls

Also now have 4 scuffed wheels with gouges out of them thanks to careless fitting. Garage owner agreed to 4 wheel refurb and no charge for fitting them so at least they are wanting to "make good" their fcukup. Still annoying though.

[doughboy]

Originally Posted by jke11y

Also now have 4 scuffed wheels with gouges out of them thanks to careless fitting. Garage owner agreed to 4 wheel refurb and no charge for fitting them so at least they are wanting to "make good" their fcukup. Still annoying though.

Plonkers who can't get RFTs off - they are so stiff to get off that the tyre machine guide arm bends under the strain, if the fitter doesn't allow for this the the metal guide hits the rim. Getting them off is much harder than putting them on.

I had 3 rims damaged like this at National Tyres a few years back, they paid for repairs but its the hassle of it all.

Event tyres use plastic coated guides to prevent damage.

[MEGA]

Originally Posted by doughboy

Wrong way round mate.

Smaller rolling radius makes your speedo overread, i.e read 65 when you're doing 60.

Thats what I meant, just not what I wrote

In the case of the OP, he's going to be lowering his speed readings because the overall rolling diameter has increased slightly.