[White1SS]

Originally Posted by arpad_m

My car received some fresh PS4S rubber yesterday, the old tires were from early 2019.

275/35/20 in the front and 315/30/20 in the rear, zero issues with TC or Stabilitrak, as expected.

Tangibly more dry traction and less noise, what's not to like (...well, the new fronts were unfortunately made in France and not South Carolina because of Michelin's weird distribution of manufacturing, not much I could do about it)

Did you put the 275's on 10" rims ? If so, do they look as they should, or do they look a bit stretched ?

[ZPirate]

Originally Posted by White1SS

Did you put the 275's on 10" rims ? If so, do they look as they should, or do they look a bit stretched ?

I was wondering the same thing. Why not stick with the 285s.

[arpad_m]

Originally Posted by White1SS

Did you put the 275's on 10" rims ? If so, do they look as they should, or do they look a bit stretched ?

They look just fine, a little bit more stretched than the 315s in the rear, and a bit of stretch up front actually helps with steering the PS4S and its softer sidewall more precisely. IMO these aren't overly stretched at all.

Originally Posted by ZPirate

I was wondering the same thing. Why not stick with the 285s.

Because this is a non-1LE SS and the 1LE / ZL1 sizes you're implicitly alluding to (285/30/20 and 305/30/20) are very different from my stock settings. I used to have 285/35/20s in the front, but the driver side was rubbing a bit at full left lock (there is some metal bracing directly behind the liner, and I was afraid it'd wear through to the metal).

In general I'd like to stay as close to the OEM front:rear ratio as possible.

Here are some pics, apologies for the dirty wheels/tires and the messy garage, but next week the car is finally going to Finishing Touch in Maryville for an exterior makeover (I figured it was due after 6 years )

[White1SS]

That doesn't look bad at all. I want to go with the same size tires when it's time, but was really not sure about the look of a 275 on a 10" rim. I can't find a 9.5" rim in something I like, which I think is the perfect size for a 275. I've also considered going with a 9" front with 275's, and a 10.5" rear with 315's so the tire stretch would look about the same in the front and rear. I've also really grown to like my factory silver SS rims, and have thought about just going with a square 285 set-up with my factory 9.5" rears, and getting another 9.5" set for the front, adding a 15mm spacer in the front for proper clearance and poke.

[arpad_m]

Originally Posted by White1SS

That doesn't look bad at all. I want to go with the same size tires when it's time, but was really not sure about the look of a 275 on a 10" rim. I can't find a 9.5" rim in something I like, which I think is the perfect size for a 275. I've also considered going with a 9" front with 275's, and a 10.5" rear with 315's so the tire stretch would look about the same in the front and rear. I've also really grown to like my factory silver SS rims, and have thought about just going with a square 285 set-up with my factory 9.5" rears, and getting another 9.5" set for the front, adding a 15mm spacer in the front for proper clearance and poke.

Yeah, 9.5" would be a bit closer to ideal fit than 10" with a 275mm tire, but again, these are PS4S tires, sidewall stiffness does matter, too. Oh, and in these sizes, the front and rear sidewalls have almost exactly the same physical height, so they look very good from the side as well as driving great. (Interestingly, I have more traction with these 315s, I can floor it and hook from high 20s vs about 40-45 with the old setup, probably because of the fresh compound. They may be even better, but I haven't tested them properly just yet.)

I can see the allure of a square setup, but I wouldn't do 15mm spacers, my wheel calculator shows you will have significant front poke with the stock (rear) wheels, because 285/35/20 tires will stick out 21mm more than the stock fronts, see here (I subtracted 15 mm from the stock offset to accommodate your theoretical spacer).

[White1SS]

I used this site and came up with about 13mm more poke, did I calculate something wrong ?


https://www.willtheyfit.com/index.ph...9.5&offset2=24

[arpad_m]

Originally Posted by White1SS

I used this site and came up with about 13mm more poke, did I calculate something wrong ?


https://www.willtheyfit.com/index.ph...9.5&offset2=24

No, everything matches up. Your site only mentions the rim poke (at 13.7mm), but your selected tire will stick out an extra 7mm on top of that, which also means your tire will roll over a bit as it's slightly too wide for 9.5". The site I used lists both wheel and tire poke.

[ZPirate]

Originally Posted by arpad_m

Because this is a non-1LE SS and the 1LE / ZL1 sizes you're implicitly alluding to (285/30/20 and 305/30/20) are very different from my stock settings. I used to have 285/35/20s in the front, but the driver side was rubbing a bit at full left lock (there is some metal bracing directly behind the liner, and I was afraid it'd wear through to the metal).

In general I'd like to stay as close to the OEM front:rear ratio as possible.

I forgot that your car didn't start out as a 1LE even though it has 1LE wheels. Makes sense to try to keep the ratios as close as possible.

I would like to go to 315s in the rear of ZL1 when I replace the tires.

[White1SS]

Originally Posted by arpad_m

No, everything matches up. Your site only mentions the rim poke (at 13.7mm), but your selected tire will stick out an extra 7mm on top of that, which also means your tire will roll over a bit as it's slightly too wide for 9.5". The site I used lists both wheel and tire poke.

Gotcha, thank you. I knew I had to be overlooking something. It would still be less overall poke than a 10" MRR/1LE with a 285 though ?

[arpad_m]

Originally Posted by White1SS

Gotcha, thank you. I knew I had to be overlooking something. It would still be less overall poke than a 10" MRR/1LE with a 285 though ?

Yes. The difference is 3mm, not much but visible.

[2SS Capt]

Originally Posted by arpad_m

They look just fine, a little bit more stretched than the 315s in the rear, and a bit of stretch up front actually helps with steering the PS4S and its softer sidewall more precisely. IMO these aren't overly stretched at all.



Because this is a non-1LE SS and the 1LE / ZL1 sizes you're implicitly alluding to (285/30/20 and 305/30/20) are very different from my stock settings. I used to have 285/35/20s in the front, but the driver side was rubbing a bit at full left lock (there is some metal bracing directly behind the liner, and I was afraid it'd wear through to the metal).

In general I'd like to stay as close to the OEM front:rear ratio as possible.

Here are some pics, apologies for the dirty wheels/tires and the messy garage, but next week the car is finally going to Finishing Touch in Maryville for an exterior makeover (I figured it was due after 6 years )

arpad_m, are you getting any rubbing at all with the 275/35s now? Also, I know I've asked you this before but can't remember, are those OEM 1LE wheels or MRR 017's? (since the fronts have slightly different offsets)?

Those tire sizes are what I would like to go to next time I need tires but don't want any rubbing...

[arpad_m]

Originally Posted by 2SS Capt

arpad_m, are you getting any rubbing at all with the 275/35s now? Also, I know I've asked you this before but can't remember, are those OEM 1LE wheels or MRR 017's? (since the fronts have slightly different offsets)?

Those tire sizes are what I would like to go to next time I need tires but don't want any rubbing...

No rubbing with the 275/35/20s. The driver side 285/35/20 was cutting it close with the strut perch and rubbing ever so slightly at full left lock, while it cleared the liner on the pass side.

The only reason I see for the rubbing is that metal bracket I mentioned above that pushes in the driver side liner a tiny bit (we are talking an eighth of an inch or so here). Your car is newer and may not even have the exact same clearance issue.

These are OEM 1LE wheels.

Note that I can only warrant for no rubbing with these specific PS4S tires, others may be slightly taller/wider even at the exact same nominal 275/35/20 size.

[arpad_m]

Originally Posted by ZPirate

I forgot that your car didn't start out as a 1LE even though it has 1LE wheels. Makes sense to try to keep the ratios as close as possible.

I would like to go to 315s in the rear of ZL1 when I replace the tires.

Do you want to leave the fronts at 285 or move up to 295?

[2SS Capt]

Originally Posted by arpad_m

No rubbing with the 275/35/20s. The driver side 285/35/20 was cutting it close with the strut perch and rubbing ever so slightly at full left lock, while it cleared the liner on the pass side.

The only reason I see for the rubbing is that metal bracket I mentioned above that pushes in the driver side liner a tiny bit (we are talking an eighth of an inch or so here). Your car is newer and may not even have the exact same clearance issue.

These are OEM 1LE wheels.

Note that I can only warrant for no rubbing with these specific PS4S tires, others may be slightly taller/wider even at the exact same nominal 275/35/20 size.

Gotcha, still makes me a tiny bit nervous, I have MRR017's which are +23 offset vs. +20 OEM offset so my wheels sit 3mm inboard further... That 3mm MIGHT mean the difference from rubbing or not rubbing... I would really love 275/35 fronts and 315/30 rears as that would put me damn cloase to OEM SS specs (wheel/tire height) (as you know)... Plus 315's out back would be great! (I hated my 275's, Love my 305's but even a touch wider (0.40") would be great with 315's!)

Honestly, I'll probably go with the Atturo AZ850's again, I never drive in the rain, they balanced great and they hook nice, and you simply can't beat the cost... So I can have fun burning them up without much guilt!