15s to 17s - Handles differently! Advice needed...

[andy_vw 0]

Hi all,

 

Just swapped my 195/50/15 setup for 205/40/17 setup.

 

Basically it doesnt seem to handle as well & a bit twitchy at high-ish speeds while cornering.

 

It's on koni adjustables - lowered 40mm I think.

 

What can I do to get my handling back?

 

- Lower the car some more? (Change springs...?)

- Adjust the damping?

- Get an alignment done & get it set-up correctly?

 

Any advice would be great :)

 

Cheers,

Andy.

[CorradoVR6-Turbo 0]

Check your alignment first and tyre pressures,it should handle just as well or not better with 17" (what have i started!)

[craziscot 0]

Mine was about the same when I changed up to that size wheel/tyre, it just felt a little more sluggish and harsh. Got used to it now but considering dropping down to 16s to get back some of whats been lost.

[Taggart 0]

Could be something as simple as the type of tyres.

[andy_vw 0]

The 15s were bridgestone potenza RE720 & the 17s are Toyo proxes T1-S...

 

What sort of camber do people run? If any at all?

[Bobby 0]

whats the weight of the 15" wheel and the 17"? i found the 17" to have a more responsive turn in than the 15" with 205/50, but like you said more twicthy in the wet on 17" and slower pickup deppending on wheel and tyre weight.

[Jim Bowen 1]

are they the correct offset, this can alter handling

[khurrado 0]

camber adjustment?

[Kevin Bacon 5]

The 15s were bridgestone potenza RE720 & the 17s are Toyo proxes T1-S...

 

What sort of camber do people run? If any at all?

 

You've gone from a very good tyre with a nice tall, forgiving side wall, to a not so good tyre with a much shallower side wall, so unfortunately there will be sacrifices to make when upsizing rims. T1-S are very soft, so I'm surprised you're having issues. it's a forgiving tyre ride quality wise.

Try dropping the pressures to 32psi front and 30 rear. Ignore the 36psi guideline on the door sill sticker, that's way too high, especially for 17s.

 

Ideal camber if lowered around -40mm is -0.8 to -1.

 

The weight of your 17s will have the biggest influence on handling and feel, and 17" tyres on average weigh 20lbs each.....it all adds up. Try turning up your damper rebound half a turn to compensate for the increase in unsprnug weight.

[A20 LEE 0]

its perfectly normal. The rear in particular will feel much twitcher. You'll get used to it in a couple of days, there no lack of grip. Just slowly build up your confidance in the new set up.

[GIXXERUK 0]

as above , it will feel twitchier purely because there is less side wall on the tyre to absorb bumps and roll on the corners , its just a confidence thing ...enjoy

[Kevin Bacon 5]

Mine doesn't feel twitchy on 17s at all ;-)

[GIXXERUK 0]

Mine doesn't feel twitchy on 17s at all

mine doesnt , it feels planted , maybe a little vague in a straight line (typical c trait)

 

but maybe after coming from 15" with big spongey tyres makes a difference, never having had 15's i can only guess

less give in a smaller side wall so you do get more feedback from 17's

 

 

and yours will feel different kev because each wheel weighs about the same as an ant :-)

[andy_vw 0]

Thanks for the advice guys...

 

cheesewire - Reduced the tyre pressures from 36 to 32 & 30, seems a little better.

 

 

 

Think I'm going to get a set of -60mm springs for it & get the alignment set up.

 

Won't be for about month though!

 

I'll do some measurements at the weekend - difference in the weights of the wheels, try & see the affect on the ride height etc

 

Cheers,

Andy.

[Kevin Bacon 5]

and yours will feel different kev because each wheel weighs about the same as an ant :-)

 

LOL! :lol: Not quite that light, a damp sponge perhaps :-)

[The_Dude 0]

Won't the fact you have a larger contact surface but still the same weight of the car pushing the tyre onto the road mean that you will have less pressure per cm2 to give grip? Or am I talking bullpoo? :)

[Kevin Bacon 5]

No that's correct, the classic Elephant's foot versus stilletto heel scenario (skinny tyres better in snow/ice etc).

 

But in this case, you are talking bullpoo cause 205/17s are no wider than 205/15s :lol:

[GIXXERUK 0]

No that's correct, the classic Elephant's foot versus stilletto heel scenario

 

 

or... the working boot versus the ballet shoe :-) our wheels versus your anorexic wheels kev

 

the size of the sidewall on a tyre plays a BIG part in the handling/feel

[CazzaVR 0]

Yeh, 17's tend to be more grippy.

 

Andy, I noticed a big difference when I swapped the 17" Kahns to the G60 BBS rims that were on it when you bought it. The ride was improved and the car felt quicker and more nimble.

 

You will get used to them though. 16's are the best compromise I reckon. Will change mine eventually.

 

Car running OK now?

[The_Dude 0]

No that's correct, the classic Elephant's foot versus stilletto heel scenario (skinny tyres better in snow/ice etc).

 

But in this case, you are talking bullpoo cause 205/17s are no wider than 205/15s :lol:

 

Got told that in college by my tutor, always thought there was something a bit awry with that statement....think he was just anti-modding.

[andy_vw 0]

Yeh, 17's tend to be more grippy.

 

Andy, I noticed a big difference when I swapped the 17" Kahns to the G60 BBS rims that were on it when you bought it. The ride was improved and the car felt quicker and more nimble.

 

You will get used to them though. 16's are the best compromise I reckon. Will change mine eventually.

 

Car running OK now?

 

It's running sweet as a nut now - still just needs the timing seeing to...

 

I still think its partly a ride height issue - as it's slightly higher than it was on the 15s... It handled beautify with the old set-up!

 

Ah well, I'll either have to get used to it or re-think the set-up...

 

Andy.

[StuartFZR400 0]

Andy, first off I hope you record the setting you used on the 15's and now the new setting on the 17's if you've got coilovers. Secondly I cant see why there are so many threads jibbering on about loosing grip etc - the weather conditions etc are having a huge say at the moment.

 

Onto the important stuff, I know you've sorted it now, but always be aware of what everyone has told you here; there are so many factors that effect the handling. Dropping the tyre pressures will have made a huge difference if you were up at 36psi. Someone mentioned offset, thats obviously going to make a big difference too.

 

Being on the 205 wider tyre and with a much stiffer tyre wall, the 17's are much less forgiving and you tend to get a lot more 'tramlining' - that is to say that the car feels twitchy and will even follow ruts in the road and feel nervous over white lines.

 

Overall the 17's should give better handling on most roads, but expect a rougher ride - its choice and a compromise at the end of the day - hence so many peeps go for 16's. Took me a long while to get used to changing from 17's back to 15's - finally found a decent tyre and pressure setup.

[dr_mat 0]

Want more grip? Lower the tyre pressure. Want taughter handling? Increase the tyre pressure .. the choice is yours!

[RobMulvey 0]

Have you noticed much of a change in your speedometer and odometer readings, and you mpg with the change from 195/50R15 to 205/40R17?

[ben16v 0]

Have you noticed much of a change in your speedometer and odometer readings, and you mpg with the change from 195/50R15 to 205/40R17?

 

doubt you`s notice it mate