Any new autocross tires on the horizon?

[GThomas]

Hey guys,

About to get a set of Rivals (225/45/15) on the KoseiK4R (15x8 only that i know of that fits over the UUC BBK). I had the new Direzza ZII's (205/50) on 16x7's for this past year and really enjoyed them but felt with the large sidewall and small contact patch of the 50's that 15x8's would be better.

Does anyone know of any new tires for 2014 or wheel selection that I should wait on before i pull the trigger on this setup?

[E30 Racer]

Looking for a street tire or the real deal?

[GThomas]

Went with Rivals on 15x8's. Street tire class is the most competitive in my chapter and I like driving to the events with them on already.

[tinkerputzer]

Let us know how you like them on an 8. My next set of tires will probably be rivals too. Just trying to decide if i want to go with 205's or 225's. I'm on 8's too.

[R3Z3N]

If you are on 8s I would use 225. 235 would be ideal.

[Wh33lhop]

If you are on 8s I would use 225. 235 would be ideal.

225s on an 8 may not actually gain you any time over 205s, depending on how wide rivals run.

[Cabriolet]

225/45/15 RS3 fit very well on 7 inch rims if you are running 8's at taking the points 235s should be the size to run if you can get them in your size

[tinkerputzer]

225s on an 8 may not actually gain you any time over 205s, depending on how wide rivals run.

Pretty much what the recent tire comparison in grm said. Wheel width should be equal to or greater then tread width. Iirc 225 rivals are 8.5" tread width and 205's are 7.8" That being said i still want to hear op's impressions of the 225's on 8's.

[Wh33lhop]

225/45/15 RS3 fit very well on 7 inch rims if you are running 8's at taking the points 235s should be the size to run if you can get them in your size

It varies between tires. Some run wider than others.

225 RS3s are much better on 8" rims than 7". They were about square on my 8s. The 205 R888s that I ran on the 8s afterwards were also square, as they run wider.

[Wh33lhop]

Pretty much what the recent tire comparison in grm said. Wheel width should be equal to or greater then tread width. Iirc 225 rivals are 8.5" tread width and 205's are 7.8" That being said i still want to hear op's impressions of the 225's on 8's.

Yep, 225 rivals weren't any faster on 8s than 205s. With the 225s on 9" wheels they picked up a lot of time though.

This is a problem everywhere. People try and stuff as much rubber on their wheels as they can, and eventually find out that it isn't any faster than properly sized stuff.

[Cabriolet]

It varies between tires. Some run wider than others.

225 RS3s are much better on 8" rims than 7". They were about square on my 8s. The 205 R888s that I ran on the 8s afterwards were also square, as they run wider.

true they(r-s3) are designed for a 7.5" rim so they will work on 8's perfectly. in the bmwcca it's all about saving points so the extra 4pts for the rims sucks when u are running the same rubber. but scca is very different and i defer to your opinion on running that wide.

[Wh33lhop]

true they(r-s3) are designed for a 7.5" rim so they will work on 8's perfectly. in the bmwcca it's all about saving points so the extra 4pts for the rims sucks when u are running the same rubber. but scca is very different and i defer to your opinion on running that wide.

Extra points always suck, but that same rubber's properties will vary greatly depending on your wheel width. A 225 on a 9" will be much faster than a 225 on a 7".

[R3Z3N]

^Agreed. With a lower HP car, one must also think about tire/wheel combo mass. For those that are not following wheelhops and cabs conversation, essentially a narrow tire on a wider rim is generally ok (to a point) but a wide tire on narrow wheels is slower. Another thing to think about is the horsepower of your car, vs tire mass, hence why going to something absurd like 10s all around will probably slow our cars down.

My old Z1s (235) on a 8.5x17in rim perform just about perfect, and are stretched ever so slightly (quite close to square profile honestly), and z1s are said to run wide.

[tinkerputzer]

This is a problem everywhere. People try and stuff as much rubber on their wheels as they can, and eventually find out that it isn't any faster than properly sized stuff.

Also i think the proper sized tire gives much better feedback to the driver.

[klodkrawler05]

^Agreed. With a lower HP car, one must also think about tire/wheel combo mass. For those that are not following wheelhops and cabs conversation, essentially a narrow tire on a wider rim is generally ok (to a point) but a wide tire on narrow wheels is slower. Another thing to think about is the horsepower of your car, vs tire mass, hence why going to something absurd like 10s all around will probably slow our cars down.

My old Z1s (235) on a 8.5x17in rim perform just about perfect, and are stretched ever so slightly (quite close to square profile honestly), and z1s are said to run wide.

This is a good point as well, at some point the weight/resistance/extra track width of a wider tire/wheel will slow you down, however I'm surprised you feel that a 10" wide wheel is that point, seems that even the 100hp miata guys find 9-10" wide wheels with 225 street tires or 275 wide slicks are still faster than anything narrower.

One other thing to consider would be gearing advantage, the 235 on a 17 that you mention (I assumed 235/40/17) is 24.4" tall while both the Hoosier 275 and the rival 225 are only 23" tall, that helps lower your center of gravity and also provides a bit more grunt out of corners vs the taller 235

of course if you're already hitting the rev limiter in 2nd regularly then the shorter tire probably isn't going to help as much but if you typically aren't hitting the limiter in 2nd the gearing may help!