i wanna ask about tyre sizes......need help plzzzz

[One]

hey i wanna ask about S3 tyres.....wanna get new ones, 245/40 back and 225/40 front....u thnk that is a good idea? is it better if the i get 235/40 on the back?

some one told me that the car tramlines more if u put 235/40 ......what does that mean?
any other effects on handling and performance?
any suggesyions?? what about spacers? better if i get 235 and put like 10mm spacers?? and how do spacers affect performance and handling.... /ubbthreads/images/graemlins/confused.gif
thnxxxxxxxx ALOT!! /ubbthreads/images/graemlins/beerchug.gif

 

[jimboA3]

As far as im aware it aint a good idea put different size tyres on a quattro car , why dont you stick to what theye were on previuosly? /ubbthreads/images/graemlins/beerchug.gif

 

[One]

probably stick with 225 but put spacers on back.....

 

[jojo]

One, I take it you have an S3, max rear tyre size you can go is 255 and 235 for the fronts, you will have to do a bit of maths regarding the profile size though to keep the rolling radius the same or I think within 1.5% to keep the haldex system happy. Tramlining is when the car steers itself due to irregular road surfaces, so by running wider and lower profile tyres, there is more tyre on the road and when the camber on the road changes, the car tends to follow it. Spacers will give you a wider track, (eg. 10mm spacers will give you a 20mm wider track) and puts a little more stress on the wheel bearings over time. The wider track should also benefit handling, but I'm sure this is minimal... most people put spacers on to clear big brakes or fill the arches up to give a better stance.

 

[One]

hmmm.....for me i wanna just improve the cars stance and look by widening the back....the front is fine dont wanna change anything there.
so keeping 225/40 on front.....what would shld the profile be on 235...?

or should i just forget about the whole gettin bigger tyres thing and just put spacers on back...?

 

[jojo]

I would just get some rear spacers and some matching longer bolts then. /ubbthreads/images/graemlins/beerchug.gif

 

[One]

10mm spacers would be enough? or 15 would look nicer?

 

[One]

225 are tooo thin i dont like them.....im gonna get 235/40 rear and front....then put 10mm spacer on back....
i thnk that would give a hell of a buffed up look for the car, much nicer.

anyone has tried this? send me pic if u did. /ubbthreads/images/graemlins/smile.gif

 

[RichA3Turbo]

On what wheels? What width? If were talking standaard S3 Avus, then thats just going to look silly as the tyre will be too wide for the car...

Rich

 

[jojo]

I think he has the 18s

 

[dunk]

wider tyres at the back compared to the front will increase understeer.

the car doesnt need 225 let alone anything bigger in terms of grip - excess tyre width increases tramlining and tyre noise and drag, but cosmetically 235/40/18 fill the arches better, and protect the rims more than 225 - the rolling radius is within 1.5% so is ok

you should use the same tyre size front and back on a fwd or 4wd car.

if you want to fill out the arches, you can use spacers, or adjustable tie bars at the rear top particularly if you have gmbh suspension or have the car lowered, which push out the top of the rear wheels, reducing excess negative camber and making the car look a lot better.

physically you can fit 255/35/18 on, but it messes up the ride and handling too much

 

[One]

nop i got 17's.......PCW rims.

anyone here has 235/40 allround? on 17's.....cuz that would just solve my dilemma

 

[jojo]

I see, with 235/40's the Rolling Radius(RR) would be reduced from factory settings, so the car would sit lower, and the arches not as filled. You really need 245/40 to get the proper RR, but I wouldn't think your rims are wide enough... they will go on, but the tyre walls will look ballooned up, reducing its effect as a low profile tyre.

 

[AndybS3]

As long as you stick to the same profile all round you could run whatever width you like front or back if it's just looks your trying to improve 225,235,295/40/17 all have the same R/R. I would think the only thing to be affected by lowering the profile would be the speedo

 

[speedyp]

Not true!
The profile is the %age of the width, so a 225/45 has a total sidewall height of 101mm & a 235/40 has only 94mm.

You need to match correctly for the speedo to be correct!

 

[RichA3Turbo]

Yep... Keeping the 'same' profile and increasing the width is impossible as proficel is a percentage of width (as peter says) 225 17's need 45 profile, 225 18's need 40 profile and 235 19's need 35 profile.

Rich

 

[speedyp]

There's a first..... I actually beat Rich to a post!!! /ubbthreads/images/graemlins/laugh_roll.gif /ubbthreads/images/graemlins/laugh_roll.gif

 

[RichA3Turbo]

/ubbthreads/images/graemlins/grin.gif

 

[jojo]

[ QUOTE ]
PeterS3 said:
Not true!
The profile is the %age of the width, so a 225/45 has a total sidewall height of 101mm & a 235/40 has only 94mm.

You need to match correctly for the speedo to be correct!

[/ QUOTE ]

Peter, you have to times the tyre walls by 2 cos' the wheel has tyres at the top and bottom, so the difference is 202.5mm for 225/45 and 188mm for 235/40... I suggested 245/40's(196mm) to bring the rolling radius to within the 1.5% needed to keep the haldex system happy, before anyone tells me the figure are over 1.5%, you need to add the size or the wheel to these figures, which is aroung 425mm for a 17" wheel and work it out from there. Anyone else can confirm what I've just said hehe!? /ubbthreads/images/graemlins/crazy.gif

 

[One]

ok...now im lost guys.....u sayin i cant put 235/40 cuz it would screw up haldex system?
would they keep R/R within 1.5% or not?

thnx

 

[One]

so can i just go from my standard 225/45 to 225/40??? or do i have to go to 235 to lower profile to 40....?!?!?!?
ehhehe

 

[jojo]

ok, when I refer to keeping the same rolling radius, I mean the same for front and back, so all the wheels roll at the same speed, as the haldex kicks in when it senses one of the axles/wheels travelling at different speeds to the others. You can run 235/40 or 225/40 if you like, but all four tyres need to be this size to keep the haldex in check. If you are running 225/45 tyres at the front, to have a wider rear tyre, you need to reduce the profile to match the RR of the fronts as close as possible, in this case 245/40 would be ideal... does this make sense? /ubbthreads/images/graemlins/crazy.gif

 

[One]

thnxxx.....now i get it.
gonna go with 235/40 on all four. then put spacers on back, maybe 10mm.

probably make the car a bit slower...but its ok.

anyone thnk its better i put 225/40 on all four? with 10mm spacers on back?

 

[One]

????????????!!!!!!!!!!???????!!!!!!!

 

[jojo]

Just go with the 235's and have the 10mm spacers on the back. /ubbthreads/images/graemlins/beerchug.gif I'm currently running 19" wheels with 235/35's and 5mm spacers on the rear, plenty of room /ubbthreads/images/graemlins/wink.gif