Got some race rubber for the FoRS

New meats arrived today:

235/40-18 Bridgestone RE-71R's on 18x8 Sport Edition P4's. 7 lbs. lighter per corner than the OEM rubber.

Anyone have a tire pressure recommendation for the 'Stones? The OEM door sticker says 46 psi.

Didn't take long, did it?

It was a financial decision. I wore out the Fiesta's front tires in 5000 miles and 3 autocrosses, and these larger 19" Michelins cost $250 each. I really don't want to be spending $2K a year on tires and be slower as well.

My 2950 pound Cobalt didn't want a lot of pressure on a warm but not blistering day at Hallett. 32-ish hot, front. Rears a bit more.

I have to run the Cadillac at 36-38 to keep the shoulders happy. I suspect you'll do best at the lowest pressure you can keep the shoulders happy at.

Much excitement has just been created.

In reply to jstein77:

Similar in size and weight to my CS 350z, start in the highish 30's (38psi) and drop a pound per corner until rollover (in the front). Rears in the RS you may want to just match to the front (it's not as understeery as my buddies WRX on the same tires)

Thanks, guys!

jstein77 wrote: The OEM door sticker says 46 psi.

Do other new cars have recommended tire pressures this high? I've never seen or heard of such a thing before this on a street car. I could even almost understand if it was so on cars like the Prious, and I've heard of that for track pressures, but for the street...Wow.

Congrats on the stick though...Should be fun.

jstein77 wrote: Anyone have a tire pressure recommendation for the 'Stones? The OEM door sticker says 46 psi.

You sure you aren't looking at the max load PSI? The car can't possibly need 46psi with the regular load.

You never quite know... Some car / tire combos need a lot of pressure, others hate high pressure. On my Jeep, my summers are quite happy and wear pretty evenly with around 44 psi cold up front and around 36 - 37 cold in the rear. On the other hand, my snows are slightly lower load rating (106 vs 109) and narrower (235 on 7" wheel vs 255 on 8" wheel) and yet they like less pressure (even though I'd expect them to want more pressure). They feel good (but wear slightly to the center as if they've got too much pressure) with about 37 - 38 psi up front and about 30 - 31 in the rear (cold pressure). Total diameter of both sets of tires is identical, only difference other than width is the summers being on 17s and the snows on 16s.

In reply to Harvey:

A quick search show this to not be an error...Ford is actually recommending 46psi.

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In reply to rslifkin:

But what psi does JEEP recommend?

Driven5 wrote: In reply to rslifkin: But what psi does JEEP recommend?

35 psi all around on the door sticker. But the door sticker pressure isn't always optimal for wear / performance on a lot of cars (comfort is factored in). And if you're not running the exact tires the car left the factory with (and especially if you're running a different size or load rating), then the recommended pressure is even less correct.

Right. Except that I've never heard of a passenger car tire on the street that has better wear, grip, or ride (regardless of the car it's on) from running 46 psi...Which is why I find it so odd/interesting that Ford would recommend such an unusually high pressure from the factory, would like to better understand what the reason is for it, and am curious if this is something that any other manufacturers have started doing these days too. Is there something genuinely unique about the FoRS that makes 46 psi a good starting point, are they giving track spec recommendations even on the street...Or were they just doing something silly like trying to get that extra 1 'rated' mpg, make it ride sportier, or reduce straight line grip at the expense of tire wear to ease the stresses on the drivetrain?

Driven5 wrote: In reply to Harvey: A quick search show this to not be an error...Ford is actually recommending 46psi. . In reply to rslifkin: But what psi does JEEP recommend?

First Google search I did returned a thread where they quoted this from the UK owners manual.

Normal Load: -Front: 41 psi -Rear: 38 psi

Full Load: -Front: 46 psi -Rear: 46 psi

Which makes more sense to me overall. 46 as the norm has to be a mistake.

I agree that the UK recommendation sounds a bit more reasonable than the US recommendation, and is what I would probably use as a starting point if it were my car, but even that is unquestionably higher than I have ever seen from a manufacturer. Which begs the question, why?

Driven5 wrote: I agree that the UK recommendation sounds a bit more reasonable than the US recommendation, and is what I would probably use as a starting point if it were my car, but even that is unquestionably higher than I have ever seen from a manufacturer. Which begs the question, why?

Drift mode optimization.

Door sticker:

As delivered from the dealer:

Weird, huh?

Harvey wrote:

jstein77 wrote: Anyone have a tire pressure recommendation for the 'Stones? The OEM door sticker says 46 psi.

You sure you aren't looking at the max load PSI? The car can't possibly need 46psi with the regular load.

Check out a lot of European cars. Pressures in the 38-44psi range are normal.

46psi is a bit startling for a Focus, but also considering that the tires are rubberbands on wide wheels, it kinda makes sense.

The ST was lighter, but had 18s with 235/40 tires and IIRC called for 36psi all around. 46 seems a bit much. I did pump the fronts on the ST up to 40 for autocross.

Just a few more days until our Daytona autocross, and the class is filling up fast. There's a huge variety of vehicles entered in the B Street class for this event:

Talk about diversity! There are several good drivers in the class as well; Tim in the S2000, Dat in the MX-5 and Dave in the other RS are all capable of overall PAX victories.

In preparation for this weekend's autocross, I just checked the Focus's alignment. I was thinking that I would have to adjust it to get 1/2 degree of negative camber like they were talking about in the Vorschlag video. Well, that apparently won't be necessary. My car came with 1.8 degrees of negative camber from the factory. I've never seen such radical alignment on a stock vehicle.

In reply to jstein77:

Impressive. How did the toe look?

0 toe.

Hey Stephan - did you ever get yours?