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Old 03-02-2008, 01:08 PM   #1
bdi
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Default 245/40 or 245/45 tires for STU?

Alright I have been banging my head against the wall trying to figure out which way to go. The tire is going to be the Stones 01R's but what size?

I know alot of people prefer the 245/40 because of the better steering response due to the shorter sidewall but this tire lacks 2nd gear top speed. I believe it is somewhere around 56mph. Could the good feel and steering response of a 245/40 be had with a 245/45? Im thinking that if they were mounted on a 9" or 9.5" wheel then the feel should be pretty good and my top speed in 2nd would now be around 59mph. Could mean alot on those courses when there just isnt enough time to shift to 3rd. Both tires have the same section width on a 9" wide wheel (10") so overall grip should be a wash between the 2.

Thoughts? Suggestions? Feedback?
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Last edited by bdi; 03-02-2008 at 01:33 PM.
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Old 03-02-2008, 02:53 PM   #2
68Cadillac
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A properly designed autox course will not allow the fastest stock class to exceed 60 mph. The rules state this specifically.

Super Stock's PAX is .852

STX PAX is .820
STU PAX is .830

My STX car and your STU car should NEVER exceed 60 mph in an autox.

Just my thoughts.
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Old 03-02-2008, 09:13 PM   #3
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Quote:
Originally Posted by bdi View Post
Alright I have been banging my head against the wall trying to figure out which way to go. The tire is going to be the Stones 01R's but what size?

I know alot of people prefer the 245/40 because of the better steering response due to the shorter sidewall but this tire lacks 2nd gear top speed. I believe it is somewhere around 56mph. Could the good feel and steering response of a 245/40 be had with a 245/45? Im thinking that if they were mounted on a 9" or 9.5" wheel then the feel should be pretty good and my top speed in 2nd would now be around 59mph. Could mean alot on those courses when there just isnt enough time to shift to 3rd. Both tires have the same section width on a 9" wide wheel (10") so overall grip should be a wash between the 2.

Thoughts? Suggestions? Feedback?
Yo, Iman!

245/45's should be fine on your scooby. You've got enough torque so there won't be any real lag to worry about. I ran the 245/45's on my Evo last year. If you want a more responsive tire you'd need to run the Dunlop Direzza, it has a stiffer sidewall.


Dave Mac
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Old 03-02-2008, 10:20 PM   #4
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Quote:
Originally Posted by 68Cadillac View Post
My STX car and your STU car should NEVER exceed 60 mph in an autox.
Haha that's funny. "Should" should be the word in bold, not never.

Personally I am going with the 245/45 just for the 140 tread rating.
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Old 03-02-2008, 10:21 PM   #5
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My ASP car should never exceed 80mph

just my thoughts
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Old 03-02-2008, 10:34 PM   #6
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what size wheel is this going on?
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Old 03-02-2008, 11:44 PM   #7
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Quote:
Originally Posted by 68Cadillac View Post
A properly designed autox course will not allow the fastest stock class to exceed 60 mph. The rules state this specifically.

Super Stock's PAX is .852

STX PAX is .820
STU PAX is .830

My STX car and your STU car should NEVER exceed 60 mph in an autox.

Just my thoughts.
My STU car saw 6500-7000 RPMS in 3rd gear at the Dixie National Tour!!! Thats around 75mph!!!

Steven Kornhaus
STU 84
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Old 03-03-2008, 01:37 AM   #8
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Originally Posted by Crash477 View Post
My STU car saw 6500-7000 RPMS in 3rd gear at the Dixie National Tour!!! Thats around 75mph!!!
I don't doubt that you did, or that it was a fun course to drive, and probably safer than most regional courses.

My point is that Solo events are limited speed. An STU car getting to 75mph is a Solo Trials Course and could easily be protested. You wouldn't be popular, but you'd be correct.

And just so you know I'm not blowing smoke (bolding is mine):

Quote:
2.1 (2nd Paragraph)
Generally, maximum speeds in the mid 50’s to low 60’s (mph) are contemplated for Stock and Street Prepared category vehicles, and WITH LIMITED EXCEPTIONS AS DESCRIBED IN SECTION 2.2, MUST BE OBSERVED, since these are speeds with which the average driver is familiar from everyday road driving. But it is quite possible to set up a course on which speeds do not exceed 45 mph, but which is more hazardous than another course on which 65 mph is attainable.
Quote:
2.2.A.
Courses must be tight enough so that cars run the entire course in their lower gears. Speeds on straight stretches should not normally exceed the low 60’s (mph) for the fastest Stock and Street Prepared category cars. The fastest portions of the course shall be those most remote from spectators and property. Turns should not normally allow speeds in excess of 45 mph in unprepared cars. It must be remembered that sites themselves vary and not all sites will safely support the speeds shown in these guidelines (see Section 1.3). Conformity to these speed guidelines does not preclude reasonable and prudent consideration of the conditions encountered.
Personally, I'd consider the "low 60's" to be <63 mph. So looks like I was wrong there. So to the OP, I still don't think you should ever be in third gear on a legal Solo Course.
Don't forget, I'm not talking our cars (STX, STU) , I'm talking Lotus Elises and Z06's, fully prep'ed on stickies, should not exceed this speed.

Last edited by 68Cadillac; 03-03-2008 at 01:43 AM.
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Old 03-03-2008, 02:01 AM   #9
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go with 245/40 if your vehicle is lowered so you dont get any rubbing isues
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Old 03-03-2008, 08:58 AM   #10
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68Cadillac-

The reason the gearing issue was mentioned by the OP is the car with short tires would bang the rev-limited in 2nd for long periods of time on course. I've driven many STi's and I know this is an issue for the car. The OP asked for suggestions on a tire and you totally f'd up his thread. Now, make a suggestion for tires that will help the OP or go start another thread.
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Old 03-03-2008, 08:58 AM   #11
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Quote:
Originally Posted by Crash477 View Post
My STU car saw 6500-7000 RPMS in 3rd gear at the Dixie National Tour!!! Thats around 75mph!!!

Steven Kornhaus
STU 84
Our STU car spiked above 6K on the same day (was too busy looking for cones NOT to hit... to look specificially where the tach was)

there's been alot of discussion about this course at DIXIE..was it fun?? hell yeah!!!


for the OP..
I'd stick to 245/40's.... and wouldn't consider the the 45 side-wall, unless you were going to a 10" wheel.. just mho..

im real tempted to try a set of 245/35's when they become available.
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Old 03-03-2008, 09:08 AM   #12
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Quote:
Originally Posted by Scoobie Doogie View Post
Yo, Iman!

245/45's should be fine on your scooby. You've got enough torque so there won't be any real lag to worry about. I ran the 245/45's on my Evo last year. If you want a more responsive tire you'd need to run the Dunlop Direzza, it has a stiffer sidewall.


Dave Mac
Whats up Dave? Thanks for the input. You racing this year? You didnt sign up for the D.C. Pro!

Can you comment on the feel of your Evo (17x9's with 245/45) verse say some cars you have driving with 245/40? I know the STi you drove at the suby challenge had 245/40's but they were on 17x8's right?

P.S. Thanks for saving this thread.

Last edited by bdi; 03-03-2008 at 09:18 AM.
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Old 03-03-2008, 09:16 AM   #13
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Quote:
Originally Posted by nhat View Post
what size wheel is this going on?
Yea I guess this is my question. Would a 245/45 mounted on a 9" or 9.5" offer good steering response (close to that of a 245/40) and still let me take advantage of the 3mph speed increase in 2nd gear?

I wouldnt want to run a wheel bigger than a 9.5 because of weight issues so that would be the biggest.
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Old 03-03-2008, 09:47 AM   #14
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Look at Adam's times from this year. He switched to 17x9.5s after the first few events and it seems to make a big difference. I'm sure there were other factors involved as well but from talking to him he seemed really happy about his choice.
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Old 03-03-2008, 09:58 AM   #15
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Quote:
Originally Posted by 68Cadillac View Post
I don't doubt that you did, or that it was a fun course to drive, and probably safer than most regional courses.

My point is that Solo events are limited speed. An STU car getting to 75mph is a Solo Trials Course and could easily be protested. You wouldn't be popular, but you'd be correct.

And just so you know I'm not blowing smoke (bolding is mine):




Personally, I'd consider the "low 60's" to be <63 mph. So looks like I was wrong there. So to the OP, I still don't think you should ever be in third gear on a legal Solo Course.
Don't forget, I'm not talking our cars (STX, STU) , I'm talking Lotus Elises and Z06's, fully prep'ed on stickies, should not exceed this speed.
Yeah I know the rule, we looked discussed it pretty in deapth in the Dixie National Tour thread, people we wondering if it was legal.

I dont care, it was fun, I won, so im not going to protest, but someone could have easily

245/40/17 is what I run, and have been very happy with.

Last edited by Crash477; 03-03-2008 at 10:05 AM.
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Old 03-03-2008, 10:02 AM   #16
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Quote:
Originally Posted by Scoobie Doogie View Post
The reason the gearing issue was mentioned by the OP is the car with short tires would bang the rev-limited in 2nd for long periods of time on course. I've driven many STi's and I know this is an issue for the car. The OP asked for suggestions on a tire and you totally f'd up his thread. Now, make a suggestion for tires that will help the OP or go start another thread.
I did threadjack this one, huh?

OP, I suggest 245/40 17. Unless the courses you normally run on are fast then 245/45 17.
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Old 03-03-2008, 10:10 AM   #17
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Quote:
Originally Posted by 68Cadillac View Post
I don't doubt that you did, or that it was a fun course to drive, and probably safer than most regional courses.

My point is that Solo events are limited speed. An STU car getting to 75mph is a Solo Trials Course and could easily be protested. You wouldn't be popular, but you'd be correct.

And just so you know I'm not blowing smoke (bolding is mine):




Personally, I'd consider the "low 60's" to be <63 mph. So looks like I was wrong there. So to the OP, I still don't think you should ever be in third gear on a legal Solo Course.
Don't forget, I'm not talking our cars (STX, STU) , I'm talking Lotus Elises and Z06's, fully prep'ed on stickies, should not exceed this speed.



Remember not all clubs are SCCA, so not everyone follows those rules. Hell, even SCCA club courses I routinely hit 3rd quite a bit and that includes national events. So, you may not think people should be in third, but it happens quite often and the OP needs to be prepared for that. Personally, I do not mind faster courses and don't see what the issue would be.
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Old 03-03-2008, 12:18 PM   #18
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Quote:
Originally Posted by bdi View Post
Whats up Dave? Thanks for the input. You racing this year? You didnt sign up for the D.C. Pro!

Can you comment on the feel of your Evo (17x9's with 245/45) verse say some cars you have driving with 245/40? I know the STi you drove at the suby challenge had 245/40's but they were on 17x8's right?

P.S. Thanks for saving this thread.
I'm in the DC Pro now...Nancy D got me in.

The 245/45's were fine on the Evo with 17x9 wheels. The 45's are a little
more vague than the 40's in steering response. The Suby I drove at the challenge was on 245/40's on the 17x8's. Needless to say, compared to my car, it drove like a marshmallow.

1. Use at least a 9" wide rim
2. 40's for steering response/45's for gearing (you need to answer what is the most important for you given the typical courses you run on). Slalom intensive, use 40 series, straights into sweepers into straights, use 45's.
3. Consider the Dunop Direzza's, the sidewall is stiffer and they are very close in grip (as stated by the West Coast STU guys who have tested them)

I will be on the Dunlops for the first part of this year.
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Old 03-03-2008, 02:08 PM   #19
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245/35-17 could be an interesting tire to try as well, once it comes out.
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Old 03-03-2008, 02:18 PM   #20
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Way too short for an STI. Would make a good STX tire though.
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Old 03-03-2008, 02:21 PM   #21
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Way too short for an STI. Would make a good STX tire though.
agreed!
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Old 03-03-2008, 02:23 PM   #22
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^^ the thought is that you'd use 2nd/3rd..

instead fo rocking the rev limiter in 2nd.

would also keep the car right in its power band.. on most courses..

mostly just bench racing.. i reckon.
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Old 03-03-2008, 02:35 PM   #23
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Quote:
Originally Posted by BrianGT View Post
245/35-17 could be an interesting tire to try as well, once it comes out.
Should be a really good tire for a 2.5L WRX owner to try if they were doing an STU build. IIRC, 2nd topped out at 67mph on my former '06. That tire size would really improve the gearing on the WRX.

Might even be a useful size for STX WRXs.
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Old 03-03-2008, 06:20 PM   #24
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Quote:
Originally Posted by waktasz View Post
Look at Adam's times from this year. He switched to 17x9.5s after the first few events and it seems to make a big difference. I'm sure there were other factors involved as well but from talking to him he seemed really happy about his choice.
Yea I rode in his car and was amazed at how much grip and response he has. Was pretty impressed.
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Old 03-03-2008, 06:24 PM   #25
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Originally Posted by 0000-09-0233 View Post
^^ the thought is that you'd use 2nd/3rd..

instead fo rocking the rev limiter in 2nd.

would also keep the car right in its power band.. on most courses..

mostly just bench racing.. i reckon.
Yea I think a 245/35 would be tough in our cars. Even if you are the best heel toe 'r' this side of the atlantic!
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