car boots

[nervous]

hi

i wanna swap my corsa's off my bbs wheels and put on the pirrellis that are on the original gt3 wheels as i feel they might be an all round better bet (most especially since it hasn't stopped raining since i got the car) and i prefer the look of the bbs's .

so, the corsa's are 235/ 40/ 18 and 295/ 30/ 18 and the other pirrellis are 225/ 40/ 18 and 285/ 30/ 18. to save me the time of pulling the wheels yet can anyone tell me if its likely whether these tyres will fit or not? (I'm guessing the J number is the same, but I'm hoping that someone here can tell me from those sizes (its a 10mm width difference, right?)(ooo, and a slihter lower profile i guess) rather than taking the wheel off to look).

moreover, other than an increase of grip in the wet, and a decrease of grip in the dry, is my handling going to be markedly different if i switch out the tyres for this different sizing? im guessing smaller width, smaller contact patch, less grip. lower profile, less compliance, more bumpy ride? anyone help out a dunce like me?

thanks in advance folks

[pdV6]

No such thing as a "J number" - 'J' refers to the way the tyre attaches to the rim.

FWIW I don't actually know the answer, but I can't imagine that a 10mm difference on that width of tyre/wheel rim is going to make any difference at all.

[nervous]

ah, ok, thanks P.

i was thinking that 8J or somesuch would tell me the width of the wheel. god alone knows where i got that from :crazy:

thanks again

[magic torch]

I thought J was width in Inches, oh well.

Lots (probably too much) info here www.chris-longhurst.com/carbibles/tyre_bible.html

[verysideways]

Nerv - difference likely to be imperceptible. Think of the difference between a stiff sidewalled tyre (T1) versus a softer sidewall (SportContact), and think of the rolling radius between a new tyre (with 8mm tread depth) and an old one (down to 1.6m tread depth).

In the words of some american dude:
Just Do It!

[pdV6]

nervous said:

ah, ok, thanks P. i was thinking that 8J or somesuch would tell me the width of the wheel. god alone knows where i got that from :crazy: thanks again

Ah - yes! '8' is the width of the wheel in inches and 'J' is the profile of the bead (rare to find anything other than 'J' these days on road cars)

[nervous]

verysideways said:

Nerv - difference likely to be imperceptible. Think of the difference between a stiff sidewalled tyre (T1) versus a softer sidewall (SportContact), and think of the rolling radius between a new tyre (with 8mm tread depth) and an old one (down to 1.6m tread depth). In the words of some american dude: Just Do It!

thanks vs.

anyone know whether the width issue will be a factor? ie whether the rims will be the same width?

[softinthehead]

nervous said:

verysideways said: Nerv - difference likely to be imperceptible. Think of the difference between a stiff sidewalled tyre (T1) versus a softer sidewall (SportContact), and think of the rolling radius between a new tyre (with 8mm tread depth) and an old one (down to 1.6m tread depth). In the words of some american dude: Just Do It! thanks vs. anyone know whether the width issue will be a factor? ie whether the rims will be the same width?

when considering your rim, and knowing you as we all do, i would have thought the wider the better

[verysideways]

Width no problem either on such a minor change. If you are running a 10" rear a 285 is preferable to a 295 anyway iirc.

[nervous]

er, no. sorry, youre all wrong. tho i wish you werent.

painstakingly removed the wheels on saturday and took all eight to my local tyre place and the bbs rims are actually an inch wider. so the swap isnt possile, that is unless i want my tyres to come off the rims whilst im cornering. bugger. new boots it is then.

[johnfm]

Which wheels have the best tyres? Use them. The BBS don't look any better or worse than the stock wheels. The BBSs are wider, allowing serious track users to use bigger rubber. I'd just fiddle less and drive it more!!