Planet 9

Apollo · #1 04-20-2009, 04:59 PM

So look like I may not be able to get entire season on my PS2s (AXes and street). Thanks to my inexperience in the past seasons (tires are original - 12K miles), I have rubbed the outer edge of the fronts close to the point where I need to change them soon. You see, I used to push the front too much during AX.

Here is the conundrum.
For the fronts I would go one up to 245/40-18 (+1.2% in revs difference)
But for the back I have a problem - since 265/35 is too small and has smaller load rating,
275/40-18 would match the +1.2% rev difference with the fronts, BUT their load rating is 1709lb
275/35-18 seem to not be a good fit in this case and load rating is the same as 40 profile.
285/35-18 have same max load (1819lb) as stock PS2s (-1.9% in revs difference) but will they fit on stock wheels?

**KS-CS** · #2 04-20-2009, 05:34 PM

According to the NT05 spec sheet on the Nitto website, you can mount the 285s on a 9.5" rim. I have mounted 275s on my CS wheels w/o any rubbing, but I don't know about 285s. Of course, you could add spacers if necessary, but I would guess that they will probably fit okay. I'm also planning on going with the 285s over the 295s because of the XL load rating on the 285s.

DMN987S · #3 04-20-2009, 05:51 PM

I'll let you know tomorrow. I just ordered a pair of 285/35ZR19 for my Boxster, I think I saw a post by alexinhouston (?) where he had 285s on his Sport Design Wheels. I'm trying the Nitto Invos.

beez · #4 04-20-2009, 05:51 PM

Originally Posted by Apollo

285/35-18 have same max load (1819lb) as stock PS2s (-1.9% in revs difference) but will they fit on stock wheels?

If you have the standard 18" CS wheels (8"/9")... I'd be reluctant to put 285 section-width tires on a 9" wheel. The ideal wheel width for 285s is 10" and that's a big difference, imo. I think you need at least a 9.5" wheel to run 285s properly.

brad

beez · #5 04-20-2009, 05:55 PM

Originally Posted by DMN987S

I'll let you know tomorrow. I just ordered a pair of 285/35ZR19 for my Boxster, I think I saw a post by alexinhouston (?) where he had 285s on his Sport Design Wheels. I'm trying the Nitto Invos.

All of the 19" OEM wheels are either 9.5" or 10" in the rear, which is a much better fitment for 285s - that extra .5" of wheel width will make some difference in how the tire fits on the rim and how much sidewall bowing there will be - with a 9" wheel, there will be a lot with a 285-width tire.

brad

**STLPCA** · #6 04-20-2009, 08:38 PM

... and the problem with a 1,700 lb load rated tire on a 3,000 lb car (about 1,650 lbs total on both rear tires) is what?

There are bunches of advanced/instructor level drivers successfully running 275/40-18 NT-01s, which have the same 1,709 lb load rating, on their Caymans.

BTW, not a track issue, but the 245 fronts increase steering effort and reduce turning radius.

Apollo · #7 04-21-2009, 12:01 AM

So for the fronts, the biggest reason I would want to go from 235/40 to 245/40 is to reduce understeer. Backs not being 265 already going to kick me out of showroom stock AX class in my region... so my thinking was why not do small bump up in the front.

For the backs... 285 does not look like a good option, so 275 would have to do. Since I don't go above 120MPH (well only done it 2-3 times since I got the car) the reduction in the back load rating for the total of 220lb should not give me sleepless nights?

$800 for all four corners instead of $1200 for PS2s... Difference of 10 AX event fees