I think a picture comparing a 245/40/17 and a 255/40/17 RE-71R was floating around FB a few months back, they appeared to be similar in width, but I think the wheels used were 9" wide; TR listed the tread width difference between the 2 as about an inch - as a similar case, the listed tread width difference between the 245/40/17 and 255/40/17 Rival-S is only ~.2". Either way, I'm curious to see if the 255/40/17 is worth using or not.

 

I'm not sure who you contacted there at TireRack (if it was Luke, let me know!) but it might be worth asking politely if they could also re-measure the 255... "overstated" is what I'm thinking as well.


Here is the photo I posted earlier, 255/40/17 on the left, 245/40/17 on the right, both on 9" rims. That's not an inch difference, or half that, or even a quarter..

 

I went through the website initially, then heard back from someone in Sales named Jake.

Good points on the overstating; didn't think about that for some reason. I'll ask about that too and maybe go through the RRAX account this time-- it did seem a little convenient the new measurement on the more expensive tire was just enough to be wider than the cheaper tire.

 

Bridgestone Japan has some measurements on their website: http://tire.bridgestone.co.jp/potenza/re71r/size.html

All measurements are the translated "tire width," but I'm not sure what that actually refers to.
245/40R17: 249mm on 8.5" wheel
255/40R17: 261mm on 9.0" wheel
265/35R18: 272mm on 9.5" wheel
275/35R18: 276mm on 9.5" wheel
285/30R18: 287mm on 10.0" wheel

 

Could you also ask them about the 245 and 255 Rival-S? Thanks in advance

 

so is the 245 wide or the 255 narrow? need to pick a set to run on OE wheels.. may come down to a matter of exactly how tall I want the tire in this case.. for the cost, may go 245/45 for a little taller & cheaper

 

That was my thinking too! If all of those are pretty close, 255/35/18 would be the on to use, since it is the shortest one of all of them!

I still think 265s will be the best way to go, tough...

 

Hey'ya Marshall, what size rear spacers do you guys run with the NT03s?


Thanks!
Doug

 

You don't need a spacer in the rear with the NT03. We both run the 10.5, which will definitely not fit with an STU legal roll.

 

also, is the height difference pronounceable at all between the 255/40 and the 245/40?

 

IMO, there is a bit more lag out of slow corners with the 255s, 285/30- 18s would have been ideal. If you were close to rubbing with 245s, the taller 255s may have a bit of interference

With how quickly the still relatively narrow 255 Bridgestones wear out, you really don't need to determine a final tire size on the first try. In one weekend I wore about 85% of the front tread off, so there will be time to try out different sizes.

 

nowhere near rubbing with 245/40s, slight rubbing at full lock on my 225/50 daily driver tires. my scientific test gets me 3 fingers between tire and fender in front, 2 1/2 fingers in back with bald Z1ss. I've got your caster plates for a little added caster so the wheel is pulled back a touch.

I'm finding myself on the limiter a lot locally, which is why I'm shooting for a little taller. Prob can't fit 265s without rolling, not really looking to do that.

 

Completely crazy idea: Some of the Porsche drivers didn't like the idea of 255s all around and suggested writing letters to make the tire width limit an average of the front and rear. If such a proposal went into effect and in the completely, totally unlikely event that it also applied to AWD cars, 285/30R18 up front and 245/40R17 in the rear would be an interesting combo. The outside diameters are almost identical (one half revolution per mile difference) so it could theoretically work.

Would certainly look stupid, though.

85% in one weekend of autocross? Was that codriven on a super abrasive lot?

I was surprised to get 12+ days of autocross and 5000 street miles out of my 245/40R17 RE-71Rs this season. We do have relatively slippery lots here for the most part, but even the grippy old St. George airport didn't wear the tires as fast as I thought it would.

Maybe that means I just need to drive harder.

 

what are they looking to run exactly? I doubt that will pass, will result in crazy combinations and a lot of complaints.. drop the rwd guys back down to 265s, leave everything else alone - done

 

Porsche drivers just want wider tires like everyone else, but they need the width more in the front than the back.

And I agree that's unlikely to pass, and definitely wouldn't apply to AWD even if it did.