Tire size

[philip_240sx]

I've asked several ppl this question... I guess I want a few more opinions before plunking down the cash for tires & rims:

When choosing a tire size for racing, do you try to get the widest tire possible (assuming it will clear)? What are the advantages/disadvantages?

ie. In my case I can go 225/50R16 or 245/45R16

[ADAM]

you know my opinion...
:)

[philip_240sx]

Originally posted by ADAM
you know my opinion...
:)

Yes, put the big 245 steamrollers on. :D I just have to save the money for the 16x7.5 Kosei rims.

I guess it really comes down to $$$. I can buy inexpensive 16x7 rims and fit 225's OR spend twice as much on the Kosei's and fit 245's.

[Chris P]

put the 225's on........ :p

[Chris P]

better yet, try out some 185's. I hear you get better bite with narrow rubber. ;)

[philip_240sx]

Originally posted by Chris P
better yet, try out some 185's. I hear you get better bite with narrow rubber. ;)

If I didn't know better, I'd think Krispy is trying to undermine my efforts in GT4 next year... :p

[ADAM]

yeah...while the weasel krispy is planning to get 13x9 rims for some silly size hoosiers....

[philip_240sx]

Originally posted by ADAM
yeah...while the weasel krispy is planning to get 13x9 rims for some silly size hoosiers....

Hehehehe... I guess that settles it then. :) I guess the one bonus to running the 245's is I have an easily accessible source of used tires... from you. :D

[John P]

Running Adam's used 245's is as good as running 185's. They will be dead, dead, dead.

[Dave]

definitely run some 245's. General rule of thumb is run the widest rim you can fit on the car (with the smallest diameter that'll clear the brakes to keep the weight down) and use the widest rubber you can squeeze into the wheel wells. Since you don't have enough power to reallly warrant 255-275's out back, you'll probably do best best with 245's all around. This way, you'll be able to rotate your tires around the car and even out the wear as much as possible. And be prepared to flip the rubber on the rims once the outside half gets more worn than the inside half. I tend to do this about halfway thru the tread depth of the tire, though now with better camber (ie. more negative) I don't have to do much flipping.

[Chris P]

Dave, you shouldn't have to do any flipping at all with optimal settings.



Krispy..........who has ETCC BMW 330ci -6degree camber envy

http://www.redshoes-archive.com/2003/2003-06-28_Donington/D4022.jpg

[ice/solo racer]

I know what your saying krispy,those guys run what looks to be WAY to much camber.I wonder how much braking is comprimised with the tires running on the edges?inside wheel lock up on trail braking looks a little extreme some times.
My handling books tell me than anything over about 2.5 degrees of camber starts to degrade performance overall not improve it.

[Chris P]

i know a guy running a Touring BMW in russia with neg9degree's......

I dunno, what does the camber curve look like on BMW's? i've talked with a few people on this and no general consesus as to why? some think, tires, just the flavour of the month, others say camber thurst, quicker turn in, makes the car better in transitions. With regards to braking i wouldn't be all too concerned untill you start playing in the extream camber levels. But at the end of the day a viriety of conditions of come togather to make this odd alignment work.

[Dave]

I know Krispy, but the reality is very few Solo 1 competitors get their camber dialed in accurately enough to create perfectly even wear across the full width of the tire. There are compromises made with alignment settings for many of us who street drive our cars, so as a result the outside half of the tire does tend to get worn down a bit faster.

[ScotcH]

Originally posted by Dave
I know Krispy, but the reality is very few Solo 1 competitors get their camber dialed in accurately enough to create perfectly even wear across the full width of the tire. There are compromises made with alignment settings for many of us who street drive our cars, so as a result the outside half of the tire does tend to get worn down a bit faster.

For some weird reason, my tires that I used on the Legend are worn almost perfectly across the tread, with the rears being slightly more worn on the inside. Maybe I just wasn't driving hard enough :) I was running -2 front, -1.5 rear

[Chris P]

dave, i don't have any troubles with tire wear, infact mine wear on the inside which is what i like to see. Your just a wussy with your alignment :p

[ice/solo racer]

I would think that the extreme negative camber(I think anything past -3 is becoming extreme)both the turn-in and transitions would be slower because of the extra time it takes for the tire to be flat on the pavement and generating max grip.Of course braking has got to be comprimised.
I could almost understand 6-9 degrees on a completly grocery getter(with stuts,poor camber curves) because most do roll that much,but for those super stiff touring cars to run that much just doesn't make all that much sense to me.Guess thats why I haven't been approuched by any race teams to take charge of their chassis tuning;)

[Dave]

hehe...Krispy, I was running 2.5 degrees of negative camber up front and 1.5 degrees out back. Based on my tire wear I should probably be running more front negative camber, but my rears wore perfectly this year.

I'm amazed you noticed any wear at all on those hockey puck Hankooks you were riding on!!! :p

[John P]

Championship winning Hankook Hockey Pucks!!!

[Dave]

LOL...yup, they sure were! I suspect they were actually Hoosier S04's secretly stamped to look like ancient Hankooks :p

[GR8 Ride]

On the BMW, I'd have to suggest that anything beyond -3 degrees is going to cause more performance issues than solve them.

I'm running -3 degrees, and get essentially perfect tire wear. Not really any need to flip tires on the rims or anything of the sort.

The camber curve with the proper Macpherson strut up front is pretty good; you're effectively maintaining or gaining camber all the way through compression.

-6 degrees is excessive; I'd have a tough time justifying how those guys are doing it, unless it's a case of fitting ultra wide rubber under the front fenders (ie, 255 or 265s in front with un-rolled fenders).

I can't imagine -9 degrees of camber on the same chassis. Makes no sense whatsoever.

You sure we're talking camber here, and not caster?


Pat

[philip_240sx]

I may be limited in the amount of camber I can run... I lack proper camber plates on the front struts... currently I use an eccentric bolt on the lower strut mount. Later on (next year???) I plan for a full coilover setup with camber plates/upper mounts so buying adjustable mounts for one season doesn't make sense.

[Nissan Racer]

HEHE...Sentra camber!!
http://www.team-rtr.com/news/2003/newsart/03ra_05.jpg
http://www.team-rtr.com/news/2003/newsart/03ra_01.jpg

[max attack]

They do make good looking touring cars eh?.WAY better than that god awfull orange on those real time cars!:D

[Logan]

What's wrong with Orange?

[max attack]

There's a huge difference between the colour of your mazdaspeed and the real time colour Doug.
Their's is the same that the road crews use to mark for sewers,hydro lines and gas lines etc.
It looks better on the ground then it does along the bottom of race cars.

[physix]

I'm trying to find some wide wheels for the #32 pickup truck to run the 335X18 RA-1's but 18" dia. 12" wide wheels are in short supply especially with a 5X5 bolt pattern and a 4" offset.

Does anyone know of any supplier in So. Ont.?

I've been quoted at about $600 plus per wheel. Thats about $5000 for wheels and tires!!! We were running 15" steel wheels and stock car slicks for $80 and $150 resp. Thats $920 for a first set of Tires and wheels.