Don't forget about the offset rule in stock... the 18's are 50mm meaning you can only run from a 56.35 to 43.65mm offset wheel. I would assume the 19s are the same or close to it since the width of the wheel didn't change.

--kC

 

Right, but I'm not sure what the stock offset is - hoping they went to a 45-46 range so a +40 would work, since that's readily available.

Again, all speculation - we'll know soon enough! I'm going to pull a wheel off today and check the size.

 

Jason,

FWIW, earlier this season I was talking to Hertweck and Buckley about the 235 19" A6s. According to them, in their conversations with Hoosier, the *true* tire size is actually a 255. It has a wider section width & tread width than a 245 A6/V710.

 

All three are very similar in Section Width when you measure them on the same wheel width, the published Hoosier spec is done on a 9" wheel for the 235/30R19 and 8.5" wheel on the 245/35r18, here's the estimated section width for 8" wheels:

235/30R19 A6 ..... 9.8" estimated section width for a 8" wheel 25.6" OD
245/35R18 A6 ..... 9.6" estimated section width for a 8" wheel 24.7" OD
245/35R18 V710 .... 9.6" estimated for a 8" wheel 24.8" OD

Other common B-stock options:
285/30R18 A6 ..... 10.6" estmiated section width for a 8" wheel 24.9" OD
255/35R18 A6 (NEW) ..... 10.3" estimated section width for 8" wheel 24.8" OD
295/30R18 A6 ........ 10.7" estimated section width for a 8" wheel 25.3" OD

Chris H

 

Great info Chris - so the 235/30/19 has just a slightly wider section width on a 8" rim than the other 245 offerings. So I guess the tire isn't a 235 but a wide 245 (or narrow 255).
This new offering from Hoosier intrigues me. My co-driver's tire guy keeps trying to get us to switch to the Ho-Ho's...

 

That's Crazy Talk..... .......just ask Jason....

 

How many times does the "wrong tire" have to win for some people to figure it out.

I guess I can let the cat out of the bag.... The 245 V710 works so good on the RX-8 because one was used to develop that size. The construction of the tire and spring rate built into it are a perfect match to the RX-8s suspension. That and I always make sure my tires are matched perfect and staggered special.

 

When it comes to the car, I'll take your word.

 

Hey I never said we were switching -- I love how the V710's feel. The tire guy's main argument is that the Hoosiers have better availabilty (at the time the V710's were out-of-stock in the US)

 

Ok, pulled a wheel - 47lb and +47ET offset... so guessing at 27lb for tire weight, the 20lb estimate for wheel weight would seem correct. With a #47ET, seems like the wheel offset range will be 40.65 to 53.35... so I'd have to shave 0.65mm off a +40 wheel to be legal!

Other notables from the lift, there's a whole bunch of airflow refinement under the car - trays and wings and tabs to move the air around - and there's a big heatsink on the diff cover now. Pretty cool stuff, although it doesn't really apply to autocross.

Look for a scale report in a few days.

 

Post some pics if possible as well.

 

What are the advantages in the wheel offset range between 40.65 and 53.35?
Thank you,
Newbie

 

Anything else is not legal.

 

Does 40.65 offset make the track wider than 53.35?
Thank you,
Newbie

 

Yes.

 

Hope this helps explain the offset issue. Most import cars (and in reality most cars these days) have a positive offset. The numbers given above, 40.65 to 53.35 are for positive offset wheels and are really +40.65 and +53.35.

The +40.65 offset will bring the centerline of the wheel 'closer' to 0, effectively giving it a little wider track and pushing the wheel out more from the stock centerline when you mount it to the hub. The +53.35 will have the centerline farther away from 0, bringing the center of the wheel more in-board to the car when mounted to the hub, decreasing track.

A wider track isn't a bad thing in and of itself. However, if you have a wheel that is so far off from the factory offset, the car could experience premature wheel bearing failure. What offset will make this happen depends on the manufacturing tolarances of the car it goes on. Subarus, of which I have a bit of knowledge on, HATED anything > -10 to -15 offset (+40mm or lower). It's wear the bearings right down.

Offset of one's wheels is something someone should know before buying a new wheels for their car. Sometimes people just buy based on bolt patter saying "it'll fit" (and companies/"tuners" will be more than happy to sell you them this way), when they won't, or won't be the best.

Tirerack sometimes pushes the envelope on what 'fits' and 'what is right'. Over the years I've seen wheels listed on their site that will 'fit' a car, but won't necessarily be good for the bearings.

--kC

 

Not really finding anything... most 19x8's are +48, 1mm narrower than stock! I wish I could just use spacers, but the studs are so short. Maybe I can get away with 5mm of spacer. I don't want to be that guy (like the RX7 video where all 4 wheels fall off.) :D

 

I've helped someone put on 5mm spacers on an RX-8 (the ones Mazdatrix sells). There was plenty of lug length, I felt, and there was still even enough of the hub sticking out that the rims went on hubcentric.

 

Thanks everyone, now I understand.
Newbie

 

Thank you Imp.

 

What you are feeling as improved torque is likely the results of the gear ratio that has changed. Engine performance is the same as the pre 09. I believe Mazda geared it to enhance acceleration. But it now requires a shift to 3rd to hit 60mph therefore hurting the 0-60mph time.

 

Actually, I've run the gear charts and it's marginally different. And in practice, my car does 63mph at the rev limit (indicated) before hitting the rev limiter. Throttle response is improved, and I believe it does have more area under the curve torque wise. The car has different injectors, and completely different ECU mapping - so I'm quite sure there's an output difference - albeit mind-numbingly minor.

 

Thanks for posting this. Next you're going to tell us that OTS Koni Yellows were used while the 245 V710 was developed, right?

 

I have read the new R3 is slower in 1/4 and it takes longer to stop it.
R&T plus other blogs.

 

It was a joke.