Silvia Club of NSW
https://silviansw.com/forum/

what size semi slick would be most suitable for 17x7.5 or 8
https://silviansw.com/forum/viewtopic.php?f=12&t=32474		 Page 1 of 1
Author:  RamR1 [ Sat Jan 10, 2009 9:35 am ]
Post subject:  what size semi slick would be most suitable for 17x7.5 or 8
AS the title says what size would be best? i was opting for a 235/45/17 but was advised that it will have too much sidewall buldge and result in sloppy response and poor handling. Apparently semis are wider than street tires...are they? if this is the case should i be going with something a little smaller such as a 225/45/17?

I would really like to put 235/45/17 so it will match the diameter of my street tires - 235/40/18. going down to a 225/45/17 will have a 11mm difference in diameter and it might throw my alignment out and may cause srubbing. i raised the car 10mm a little while ago and this will bring it back down to scrubbing height :(
Author:  dcoghlan [ Sat Jan 10, 2009 9:50 am ]
Post subject: 
I ran 235/45/17 RE55S on a 7.5 inch wheel for about 3 years without any issues.
Author:  fergo308 [ Sat Jan 10, 2009 11:59 am ]
Post subject: 
run a 235 on the 8" rears,and a 215 on the 7.5" front for more direct steering feel.


Justin...
Author:  RamR1 [ Sat Jan 10, 2009 12:41 pm ]
Post subject: 
fergo308 wrote:
run a 235 on the 8" rears,and a 215 on the 7.5" front for more direct steering feel.


Justin...


The rims will be R34 gtt rims. Im pretty sure they are 7.5 wide. Im pricking them up tomorrow. They guy whos selling them says they are stamped with 17x8 but all the SAU guys reckon they are 7.5 so im not sure any more. If they are 7.5 would i run different widths? Same question if they are 8's. I'd like to run the same size if possible so i can rotate the tires.

Is running a narrower front recommended with same width all round?

Should have made the first post a bit clearer. :oops:
Author:  fergo308 [ Sat Jan 10, 2009 1:24 pm ]
Post subject: 
yeah,you probably should have. *shrug*

GTT wheels are 7.5" wide. I had a set for a while on my previous C34.

you'd want to run the same size all around,since the wheels are the same size anyway.

235's are really a bit wide for a 7.5" wide wheel. they will fit on,but won't be as direct as they would be on a wider wheel.

a 235/45/R17 is the closest size for maintaining the std rolling diameter.
225/45/R17's will fit the wheel better,but is slightly smaller in diameter so your speedo will be out by a few km/h. not a problem on the track,and shouldn't be a problem on the road either as long as you're mindful of it.

your 18's are larger in overall diameter already btw... so if they aren't scrubbing,you won't have an issue.



Justin...
Author:  RamR1 [ Sat Jan 10, 2009 1:45 pm ]
Post subject: 
fergo308 wrote:
yeah,you probably should have. *shrug*

GTT wheels are 7.5" wide. I had a set for a while on my previous C34.

you'd want to run the same size all around,since the wheels are the same size anyway.

235's are really a bit wide for a 7.5" wide wheel. they will fit on,but won't be as direct as they would be on a wider wheel.

a 235/45/R17 is the closest size for maintaining the std rolling diameter.
225/45/R17's will fit the wheel better,but is slightly smaller in diameter so your speedo will be out by a few km/h. not a problem on the track,and shouldn't be a problem on the road either as long as you're mindful of it.

your 18's are larger in overall diameter already btw... so if they aren't scrubbing,you won't have an issue.



Justin...


yeh sorry about that.

The only thing im really worried about is the scrubbing, dont really care if the speedo is going to be out as these rims will be for track only. Plus according to this tire size calculator i have been using it will only be about 1.722% faster that what it is reading now so meh to that.

Since it will be a smaller overall diameter wont that lower the car too? Overall diameters:
235/40/18 is 645.16 mm
235/45/17 is 643.12 mm
225/45/17 is 634.23 mm

Going by that there will be a 10.93 mm difference with 225's. Wont that lower the car by 10.93 mm??? I had to raise the car while using my street rims (235/40/18 ) 10 mm as it was scrubbing up on the fronts.

Im affraid the car will be lowered by 10.93 mm and start to scrub again and also throw out my alignment. Will this happen or will it be fine?
Author:  fergo308 [ Sat Jan 10, 2009 2:52 pm ]
Post subject: 
it'll lower the car by HALF of that dimension as you're referring to diameter differences. 5mm is so small a difference that you'd never be able to notice it.

your speedo is out NOW with the 18's on,so if that's not bothering you,you certainly won't have an issue on the track.


Justin...
Author:  God [ Sat Jan 10, 2009 3:23 pm ]
Post subject: 
Also, the car will indeed be 5mm lower, but that is completely different to lowering the suspension 5mm!

Your car will be 5mm lower, but you will ALSO have 5mm MORE clearance between wheel and arch.
Author:  RamR1 [ Sat Jan 10, 2009 4:12 pm ]
Post subject: 
thanks for the input guys!!!

225/45/17 it is then.
Page 1 of 1 All times are UTC + 10 hours [ DST ]
Powered by phpBB® Forum Software © phpBB Group
http://www.phpbb.com/