Tyre sizes

[byroncobra]

My car is fitted with Advan 255 50 16s on the rear and 225 50 16 on the front and being a really soft compound semi track tyre i want to keep them aside for track days. Rims are 16 x 9.5 and 16 x 8.

They came fitted to the car when i bought it as a roller and there's issues with the rear guards just scraping the tyre walls when i've a passenger or push hard into corners, this leads me to think that the offset isn't quite correct, but that's another story.

I'm thinking with a lower profile tyre that this may give me less ballooning with the sidewall (the tyre currently sits about 5 to 10mm wider than the rim edge) This should be enough to stop the rubbing I reccon.

There apears to be no such size as 255 40 16, I'm trying to get my head around the changes in profile as treadwidth changes. Can anyone enlighten me on an equivalent sized tyre with a lower sidewall height and subsequent "square" face, should this help solve the scraping problem?

What size sholud be matched up for the front? No clearance issues there.

Thanks

Greg

[Rog246]

Well try this link and see if it helps you
TYRESAVE: Tyre Size Calculator

A handy bit of kit

Rog

[Merv and Sharon]

Looks like an offset (as you say) issue Greg. I had the same on my Harrison. You have Dragway wheels and so do I but there are many offset possibilities. Mine are 17" and 235 and 275. I guess you can look for a lower profile tyre, increase the shockie height at the rear or mill a little off the inside of the Dragways (or sell 'em and get some other wheels?)

[Zedn]

Can you adjust the camber a little for some clearance?

By doing what you want to do you will put your speedo out of cal.

[Merv and Sharon]

The Harrison standard rear (GTR) is tricky on camber and mostly 3 degrees negative is all you can get (and more than you want for the street). To reduce that you need an adjustable upper arm such as Whiteline. I think Greg has those.

[byroncobra]

ok thanks for your responses, but I've done as much as i can to machine wheel backs, lifted the shocks, camber etc. All I really want to know is if i reduce the tyre profile should it bring the tyres sidewall back flush with the wheel rim. That should give me enough clearance i think.

[boxhead]

In my opinion, you dont want tyres to last more than about 2 years anyway (if your going to circuit race), so unless you plan on doing alot of driving, I would chew up the good ones (that is what I do)
As soft sticky rubber goes hard sitting under your bench.

[byroncobra]

Ok boxy, but the tyres on the front are already RS after only a few trips so I've gotta buy replacements anyway