92 replies to this topic

[Mike Collins]

Do you run the 13mm spacer?

 

NO

[svvs]

I think I heard someone liked those 38mm wheels because narrower profile meant less wind resistance?  No clue.  I'm not that quick.

 

I like 30 mm because I can't roll fenders well  and sometimes I get a rub with my 25 mm set.

 

Vick

[bmw251]

I have a feeling Mike was not asked the proper question........
Sooo back to my question..... I guess anyone running the 30 offset wheel from tire rack is running an illegal rim.

Greg

[Alberto]

I have a feeling Mike was not asked the proper question........
Sooo back to my question..... I guess anyone running the 30 offset wheel from tire rack is running an illegal rim.

Greg

 

no.  Go re-read the rule book.  The 25mm offset wheels provide the largest /maximum legal track width front and rear.  You can run any of the popular offsets up t 25.  You can't run a 10 or 0 offset for example.

[Brandon]

I believe what Greg was pointing to was the weight shown of the +30 wheel on TR's website (under 13#) and not necessarily the offset.

But I don't want to put words into anyone's mouth there....

 

And Vic - I believe it was Yannis who commented on being faster with the +38s (no spacers) vs. the +30/+25 wheels.
Wind resistance or something else would be debatable when considering the amount of tire that could protrude into the airstream with the maximum offset.

 

My guess would be the "lever force" (the term escapes me now) of the final spring/shock compression/rate at the end of the control arm being different with the various overall "LCA length" options.

[Sphinx]

I believe what Greg was pointing to was the weight shown of the +30 wheel on TR's website (under 13#) and not necessarily the offset.

But I don't want to put words into anyone's mouth there....

 

And Vic - I believe it was Yannis who commented on being faster with the +38s (no spacers) vs. the +30/+25 wheels.
Wind resistance or something else would be debatable when considering the amount of tire that could protrude into the airstream with the maximum offset.

 

My guess would be the "lever force" (the term escapes me now) of the final spring/shock compression/rate at the end of the control arm being different with the various overall "LCA length" options.

 

Cantilever?

[Eric Jones]

The motion ratio changes with offset. The wider the wheel sticks out, the more leverage it has on the spring. ie softer "wheel rate"

[Eric Jones]

I like the Kosei wheels. They're the only ones I can find that are low pressure cast and not just gravity cast. Should be stronger for the weight.

[Glenn Davis]

NO

  

Do I have to wait until the next expert chat to ask how you got to this set-up?

I believe what Greg was pointing to was the weight shown of the +30 wheel on TR's website (under 13#) and not necessarily the offset.
But I don't want to put words into anyone's mouth there....
 
And Vic - I believe it was Yannis who commented on being faster with the +38s (no spacers) vs. the +30/+25 wheels.
Wind resistance or something else would be debatable when considering the amount of tire that could protrude into the airstream with the maximum offset.
 
My guess would be the "lever force" (the term escapes me now) of the final spring/shock compression/rate at the end of the control arm being different with the various overall "LCA length" options.

I guess with the wheel being further outboard, you have a larger lever arm through the lower control arm to the shock. However, since the suspension is constantly altering the geometry, I'm guessing there's more going on...

[Brandon]

The motion ratio changes with offset. The wider the wheel sticks out, the more leverage it has on the spring. ie softer "wheel rate"

Bingo!  Wheel rate!  Wider track == softer wheel rate.

 

And using Sphinx's word, due to the longer cantilever, it's easier to compress the spring/apply more force quicker to the shock.

[Johnny D]

A 25 sticks out more than a 38, thus the 13mm spacers could be used for max track.

J~

[Alex Bolanos]

Those wheels listed above are pretty far above the minimum weight.  I like these here myself....

 

 

Momo podiums, 15x7 +25 offset, black or silver and available from Mazdacomp or Momo directly 

[philstireservice]

Yep - pretty far over weight.

 

Add 2 secs more fuel - eat a big sandwich before the race - add a bottle of water to the car or a few more ice cubes to the cooler etc etc.......

[Alex Bolanos]

I'm slow, need all the lap time i can get from anywhere

[Ron Alan]

Johnny and Alberto are slipping...need to read the thread

Yep - pretty far over weight.

Add 2 secs more fuel - eat a big sandwich before the race - add a bottle of water to the car or a few more ice cubes to the cooler etc etc.......

Rotating mass Phil...though I'm sure your post is tongue in cheek

This said...why is the Hoosier when a sticker faster than when shaved and a sticker? I base this on what others have posted...not personal experience!

[Alex Bolanos]

Ron: $$

[Alberto]

Johnny and Alberto are slipping...need to read the thread
 

 

I read it. I just need to work on the reading comprehension part.       

[Johnny D]

Johnny and Alberto are slipping...need to read the thread
 

 

Nop,

My reply was to explain Collins statement of 38mm offsets with no spacers on the page 1, if newbies may be thinking 38 is more.

Then Mike didn't explain why he's doing that.

J~

[Mike Collins]

38mm is the stock offset.  30mm is readily available and 25mm is a SM specific offset and the widest allowable by our rules.  the wider the offset the softer the spring rate the higher you need to run the car.....

[Glenn Davis]

38mm is the stock offset.  30mm is readily available and 25mm is a SM specific offset and the widest allowable by our rules.  the wider the offset the softer the spring rate the higher you need to run the car.....

Things that make you go hmmmmm...