Lightweight 17's?

[Original J-Pat]

There is nothing I would consider light weight that just bolts on but the TD's are very solid wheels that fit and will hold up to most any use imaginable and still lighter than stock.

I would not run wider than a 205 to 215 on an 8" wide wheel as sidewall support is very important to optimum handling and they would weigh less than a wider tire, usually at least.

215/40/17 or 215/45/17 ?

 

[PCA-1]

215/40/17 or 215/45/17 ?

215/40/17. The 215/45's add increased, additional height, something that could contribute to rubbing depending on your suspension set up.

 

[razorlab]

Nothing wider than a 215 on a 8" wide wheel? What?

I'd say nothing wider than a 215 on a 7" wide. A HP tire with a stiffer sidewall is just about perfect at 215 on a 7" wide.

225-235 would be ideal for 8" wide wheels.

 

[PCA-1]

Nothing wider than a 215 on a 8" wide wheel? What?

I'd say nothing wider than a 215 on a 7" wide. A HP tire with a stiffer sidewall is just about perfect at 215 on a 7" wide.

225-235 would be ideal for 8" wide wheels.

You are correct. I had 7" wheel in my head....

 

[RAAMaudio]

I used to run up to 235 on 17x8 but have found a bit of stretch is best, not a bunch of it, just enough to provide the best support for the sidewalls.

I am also concerned with absolute grip as much as feedback, etc....GRM did some very good testing and found they were significantly faster with narrower tires on wider wheels on that particular test of course, wheels, car, setup, all which matches my needs the best so it was a great test I could use the info from. I have 15x9 with 225 Toyo RA1 R comps and it works perfectly. I wanted to run the 225 Hoosier R comps but they were more like a 245 and would not fit in the rear and frankly looked to wide for a 9" wheel. I can also run a 205 on the rear, on 9s, if I want to lessen the grip a bit but I can do that with other methods and easier to have a sq setup, same front and rear tires and wheels.

I have 205/45/17 on 17x7 for my street setup but wish they were 7.5 or 8" wide. The Mich PS AS/3 is a pretty wide 205/45/17, a 215 in that particular tire would be much to wide on a 7.

We do need to look at the tires actual specs, not what the manf published as often not accurate for various reasons but often due to rules to get more rubber on the ground in some classes of competition.

Then there are cases where the wider tire on a narrow wheel to fit some rules is the faster way to go.

There are no set in stone absolute numbers, just ball park estimates at best in many cases, it depends on your particular wants, needs, mods, use, etc.........

A 215/40/17 on a 17x8 would look really great, probably no rubbing, really good sidewall support, etc.....

 

[razorlab]

I run the ZII SS's in 215/40 on my 17x7 and they are square, zero stretch and zero bulge.

The ZII's run wide too and also have a stiff sidewall. Working great on 17x7.

Once I go to 17x8 I will be running a 225 or 235.

 

[rodmoe]

About the only thing I noticed when I switched my 205/50/15 DZll out for Hoosiers of the same size is the Hoosiers are about 1/4 inch shorter the the DZ's were. Tires are funny . Be nice to see how they fit for ya on 17's

 

[RAAMaudio]

Stiff sidewall is also part of the equation, forgot to mention it.

I have ran 225/45/15 tires that were very clearly a 245 when measured on a 7" wheel but they were called cantilever in the product description and purposely made for a race series that limited wheels to 7" wide.

Only testing would reveal the absolute fastest tire width on a particular wheel width and for a particular need.

Driving style plays a part in this as well as monitoring temps across the tread, air pressures, alignment angle changes from stock.....

Just because it fits and looks sq still does not answer all the questions

There have been hundreds if not thousands of posts covering such things as this on various forums concerned with different types of racing and I still learn every day but have also researched a huge amount and have had at least a hundred sets of wheels and tires just in the last few years alone that I have used in many different levels of builds, street, track, street/track, etc.....and I still spend a great deal of time working out exactly the best setup I can for all my vehicles including trailers and trucks to tow them with.

 

[razorlab]

Yea I just do recreational track days. I don't race. Every body is different. Some people want every single silly second in their HPDE class and treat HPDE's like races, which I find silly but I'm not them.

I don't own a tire temp gauge nor do I care. Every .001 second means .0 to me.

Fun factor is the number one thing to me. I try not to stress about the small things other than making sure the car is operating enough to have fun and the modifications I do aren't dangerous.

 

[RAAMaudio]

Rodmoe,
I had the 225 R6 and 225 RA1 15's and the R6 would not fit under the rear of my car without major surgery and it still was a lot of work to fit the RA1 but would of been a major investment in time, body work, painting, etc for the R6.

If memory serves me right the DZ are a pretty wide tire.

Different sizes of the same tire brand and model can be quite a bit different in real measurements, some extra wide, some closer to the posted info and some narrower.

The biggest differences from molded on the side, printed specs, etc and rear measurements are mostly on race tires but the none PS Mich AS tires are very narrow for there specs and the PS version are a bit wide for their specs.

Many tires we are concerned with here can easily be compared on Tire Rack . com

 

[RAAMaudio]

Razor,
That is totally cool, I wish I was like that but have never been, it would be far easier in so many ways

Something to think about:

Tire temp gauges can really tell you a lot even on the street, make a run down the freeway, measure inside, middle and outside temps.

Hot in the middle, to much air, cold in the middle, not enough.

Hot on the inside, toed out.

Hot on the outside, toed in.

If the car is stable, not loose, not pulling, you can adjust the tire temps for the best grip and least rolling resistance.

---------

To go a bit deeper into this.

Inside and outside can be a camber issue as well but camber on the track has to deal with optimal air and if the tire is rolling over, sidewall support, etc..........

Just by taking temps right after some of my first runs on track I was able to determine I had optimized the camber, spring rates, toe, etc.....many aspecs of setting up the car and now I can leave it alone. (spring rates as I have a stock front bar and no rear one and it is working great with the rates I have but I will still play with bars in deeper levels of testing)

This is an all around setup I worked on so I can leave it alone and do well on the street and track and only have to adjust the air pressures and shocks.

If I really wanted to go all out nuts on this there is a big list of things I would be testing and logging and would have different springs, shocks, settings, etc for different tracks, my goal was a simple setup that worked very well for most everything and it does, tire temps proved it.

------------

I am working towards TT events and this will really help there as want a competitive car but am OK having a very street friendly car that might not beat everyone but I can jump in, drive anywhere in comfort and reliably while doing so.

 

[razorlab]

Something to think about:

Tire temp gauges can really tell you a lot even on the street, make a run down the freeway, measure inside, middle and outside temps.

You do have a sickness. I'm so glad I'm not like that, I would drive myself crazier than I already am.

 

[RAAMaudio]

Thanks for the complement

I would rather be whatever anybody wants to call me and be my true self which I am pretty happy with overall but it is a lifelong journey figuring out what this all means and in the end, do modded cars really matter.....

 

[razorlab]

Thanks for the complement

I would rather be whatever anybody wants to call me and be my true self which I am pretty happy with overall but it is a lifelong journey figuring out what this all means and in the end, do modded cars really matter.....

I'm not judging you at all, that was kind of the whole point of my post. Everybody views things in a different way.

If you saw me obsess over engine data logs you would say I had a sickness as well.

 

[rodmoe]

Modding cars has its perks as I only really care about getting the most out of my car I guess I will need to look into tire temps as I have for now just been playing with pressures but other better autoX drivers watch tire temps and adjust after each run..
Not sure how this fits into a thread about 17x7 or 8 inch rims but it's good info none the less. On a side not I do love my A6's once they are warm that first hard turn is fun and front to back tire pressure is kooky based on the care and feeding manual that Hoosier provides .lol
Let get back on topic though my bad ..

 

[Original J-Pat]

So running 225/40/17 should be a good fit will I get any rubbbing issues? Or does it depend on the true size of the tire since I've heard it can vary.

 

[Original J-Pat]

And Raamaudio your precision about all these details is amazing I'm glad im not that particular about those things

 

[RAAMaudio]

Tire temps are a bit off the thread but the reality is the more accurately we setup the car the better the results, properly matching tread width, sidewall support, alignment, tire pressure, temps, etc....all add up and are all used by the fastest drivers and teams.


There are those that are far more experienced and know more about this stuff than I do, I just want to share what I do know and have made work for me over the years. I have never gotten fully in sync with getting my shocks just perfect for the specific track or autocross course, I have only had different spring rates for different surfaces a few times, serious race teams will carry quite a few different ones and some different shocks as well as have finely tunable sway bars.

Since most of my cars are dual purpose I work to get the best overall setup I can and then tweak more simple things like air pressure, maybe toe, sway bar settings and sometimes camber.

That is why I am so anal about tires and everything about them, they are the link to the ground thus critically important and can make big differences with little changes that are pretty easy to figure out

-------------

Razor, I was just having some fun, I have put off the tuning thing because it is so deeply involved and I just did not want to learn it, though I know I could and be a great tuner I simply prefer not to, that is why I depend on people like you and others that have pursued and mastered such things.

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Now if I could just find some lite weight 15x8 or 17x8, 4x100, +40 or +42, low cost wheels......I can make +35 work but it would be better to run +40 or 42 for scrub radius. I can find some wheels but they do not fit over my BBKs like my 15.9's, +35. I would settle for 15x7 or 7.5 but not available either.

 

[Original J-Pat]

Tire temps are a bit off the thread but the reality is the more accurately we setup the car the better the results, properly matching tread width, sidewall support, alignment, tire pressure, temps, etc....all add up and are all used by the fastest drivers and teams.


There are those that are far more experienced and know more about this stuff than I do, I just want to share what I do know and have made work for me over the years. I have never gotten fully in sync with getting my shocks just perfect for the specific track or autocross course, I have only had different spring rates for different surfaces a few times, serious race teams will carry quite a few different ones and some different shocks as well as have finely tunable sway bars.

Since most of my cars are dual purpose I work to get the best overall setup I can and then tweak more simple things like air pressure, maybe toe, sway bar settings and sometimes camber.

That is why I am so anal about tires and everything about them, they are the link to the ground thus critically important and can make big differences with little changes that are pretty easy to figure out

-------------

Razor, I was just having some fun, I have put off the tuning thing because it is so deeply involved and I just did not want to learn it, though I know I could and be a great tuner I simply prefer not to, that is why I depend on people like you and others that have pursued and mastered such things.

-------------

Now if I could just find some lite weight 15x8 or 17x8, 4x100, +40 or +42, low cost wheels......I can make +35 work but it would be better to run +40 or 42 for scrub radius. I can find some wheels but they do not fit over my BBKs like my 15.9's, +35. I would settle for 15x7 or 7.5 but not available either.

Scrub radius? I was guna go 17x8 +38 I think is what the lowest offset the TD Pro Race 1.2's come in

 

[RAAMaudio]

I like to go a as wide as I can from outside to outside but there is a point where the offset of the wheel/width induces undesired effects on how the car behaves when turning, the proper terms are slipping my mind right now but I will post it later when I remember it. Basically it is best to have the same percentage of the wheel forward and aft of the hub mounting location in most cases though there are cars that benefit from it being different.

Stock offset is 47.5mm. when adding 1" wider wheels you would split the 25.4mm in two and add that much wheel width to each side keeping the hub centered as stock which was engineered for optimum scrub radius and the same load on the bearings in general as more load is added with more rubber on the ground...

An offset change of 5-7mm is pretty tame, going further can start causing other issues but sometimes it is not critical and sometimes the added gain of the wider track width, more tire, is worth it.

Deviating from the stock optimized setup can as above, all more load on the bearings, it can change the effective ratio of the springs and shocks and what is called scrub radius which can reduce grip.

Having flush fitting wheels and tires sure looks cool and on some cars doing so can make them better but that is pretty rare, some offset change to the outside is OK but a lot of it is not so great.

I went all out on my setup as wanted all the tire I could get on the car and run 15x9 +35mm wheels which require a 2mm spacer up front to not rub the coilover housings so a 33mm offset would be a better fit in that regard.

A 35mm or so offset in a 17x8 is not to bad, I would not want to go any further with it though no matter how cool it might look to some that put that above real performance.

A 38mm is even better as 9.5mm is not a huge amount of movement to the outside and the added 1/2" wheel width there will make it 22.2 mm wider on each side of the car which looks nice and helps deal with the weight up high on a tall car.

I try to keep it pretty close to stock but have been known to measure all the parameters and chosen to deviate quite a bit at times. I am also willing to change wheel bearings more often as I need to more than most anyway due to running sticky tires and hard driving on track, etc.....





OOPS, I was off in my other post, just started to have my morning coffee, I will correct it.