Meaty Tires Thread

[RAAMaudio]

"The stress on this and that is a bunch of nonsense but let's not get into that here"

Dear fellow members, please disregard this very misleading statement.

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In order to fit 15x9, +35mm wheels under the stock fenders required far more than just rolling and pulling but there might be an easier way though it would still not be that easy.

I cut and realigned the rear axle flanges which is a very serious effort and requires exacting workmanship to do it right and safely, even then it was a very tight fit in the rear with -1.9 camber and zero toe. I had to pull and roll as far as I could go and then remove the caulking on the seam between the fender and wheel well. Up front the wheels touched the BC struts on hard corners with really sticky tires, DIY 6061 aluminum 1.5mm spacers fixed that issue.

+35mm offset wheels are the best ones to go with in 15x9 that are available that I know of, custom offsets front and rear would be nice but $$$ and limit tire rotation options. IF, you could find something in +38 or so offset you would have to compensate up front with more spacer width to clear the struts but gain clearance in the rear.

Option 1:
The bolt on none ST rear axle comes with -1.5 camber though is a bit softer so a rear sway may be mandatory to use it, I do not use nor need one on my setup with 8k front and 7k rear Swift springs. (I actually modified a 5-way race grade rear sway bar from a prior BMW race car project, made mounts, etc then found I did not need it so did not even test it, stock front bar with adjustable end links and harder bushings used as well)

Fitting some 225 tires might work out and no so with others depending on how they are made, thick rim protector strips might get in the way, the Rival S has them on the outside and inside which I find really odd on the inside, why?

Option2:
Shims, problem is they have to be made exceptionally well, taper down very thin, two parts as inner and outer so the bolts line up without binding and they will push the wheels out further so more camber is needed and there is a point where you end up with to much rear camber.

Option3:
Flares, one has to do sheet body work and painting unless lifting the car up high for off road use
I would still keep the offset as high in number as I can to keep the geometry as correct as possible.

There was a very important reason I changed the camber that is really more important than fitting wider wheels. It was to compensate for the added front camber to keep the balance of the car where I wanted it. Just adding more front camber with so little rear camber can lead to an unstable car on very high speed corners. The safe way to build a fast race car, easiest to drive, faster lap times nearly always is going to happen with slight oversteer on slow speed corners, neutral on mid speed and slight understeer on high speed corners, not easy to achieve but the best one can do is the way to go.

I picked -2.5 front and -2.0 rear as what I considered optimal for street/track use, contact patch for acceleration and braking, tire wear and not having to change anything but damper settings. I have had to many cars requiring major changes between uses and I wanted a great all around setup and it worked out better than expected on this car I ended up with -1.9 in the rear which was well within what would work out and my car is amazing on track



Rick

 

[RAAMaudio]

I did a lot of work to run 15x9 wheels under stock fenders, if I had paid to have it done it would of been very costly, using the none ST bar costs a bit if somebody wants to try it I would recommend doing so but read the info above first

Note: I only run one chassis brace on my car, DIY $2 sq tube 2 point up front, I have built full race cars, modified cars for handling since the early 70's, had the car on a lift and had a real race shop manager look over all my work and he agreed completely it was the only brace the car needed. Save your money and spend it on things to take weight off and improve handling, braking, etc....adding unneeded weight only makes the car slower even if the placebo effect feels otherwise

 

[BronxBomber]

I did a lot of work to run 15x9 wheels under stock fenders, if I had paid to have it done it would of been very costly, using the none ST bar costs a bit if somebody wants to try it I would recommend doing so but read the info above first

Note: I only run one chassis brace on my car, DIY $2 sq tube 2 point up front, I have built full race cars, modified cars for handling since the early 70's, had the car on a lift and had a real race shop manager look over all my work and he agreed completely it was the only brace the car needed. Save your money and spend it on things to take weight off and improve handling, braking, etc....adding unneeded weight only makes the car slower even if the placebo effect feels otherwise

Good to know you're still around Rick. Not too many of the Original contributors left on this forum.

 

[LILIKE16ST]

I disagree with the statement that there isn't a negative effect with having spacers and much lower than stock offsets. In particular spacers. As far as it not putting stress on things. Doesn't matter if someone has done it 100 times if you do something wrong 100 times does that make it right? Not saying anything in particular anyone has done is wrong or right simply saying that I don't agree with the blanket statement that there's no added stress on things when using either or both.

 

[RAAMaudio]

Simple physics, once you have studied how these things all work together by reading the best suspension books written, practiced what you learn, confirmed with actual suspension engineers, etc...which I have done for close to 50 years now, there is no argument that can tread water against the reality of what we are talking about here, just how it is.

All I have done and I am still in awe when it comes to the real experts like a buddy that took a world class race team to the championship in one season using his changes to the suspension, the only real changes made and from way back in the field to winning many races as soon as he was on the team.

Back to normal cars, trucks, etc, control arms are designed to be a weak point for certain impacts to lessen the forces sent to the chassis so less damage occurs. Now you have a part designed to bend or sometimes break, all a big lever arm to it, it is far more likely to fail with far less impact or sometimes just a big bump in the road, I have seen it happen far more than once. Wheel bearings are designed to handle a certain load applied, move the point where the load is applied and they will fail much sooner and sometimes rather dramatically like in freezing up rather suddenly, not fun. King pins, knuckle mounts, ball joints, etc.....all are designed to handle a specific load applied at specific angles, change the load angles, failure is far more likely to happen much sooner and at less impact force. Chassis, same general rules apply, not designed for the added load.

I know I put more load on the chassis than the original design was intended but do it the least I can, upgrade parts as required when I can, inspect parts regularly and accept the added time and cost the maintenance will take.

My last serious project had a full tubular suspension, teflon lined monoball joints, gusseted mounts, 2-5 added supports added to each pick up point, it was a pure race car build though, $15k just in suspension not counting any labor or materials for gussets, supports(roll cage elements) and more and I had spare parts for all the critical areas.

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All that said the car with the 15x9, quality spacers and I hope really good studs, +18 offset combined, 245 sticky tires, a great deal of added stress and wear will be induced but if properly maintained and not driven tons of miles on bad roads should be reasonably safe to run for quite some time. I would however take a good look at the scrub radius and other aspects like roll center to ensure you are getting full use of the contact patch as it can start to become very compromised when offsets are pushed to far, you might be losing more time than gaining with the setup as it is. At a bare minimum I would at least make the closest runs you can, same course, same day, temps, etc with and without the spacers.

If my car I would grab a set of 15x10 6UL wheels to put those tires on, 13.5 lbs, +25 offset, very very strong, $199 each
(I did not plot out the actual fitment as decided to not add flares but then also decided if I added flares I would run the 15x11 and 275 slicks on them)

Autocross is a different world than the street or track in some cases things setup outside the norm work better, I even swapped different offset wheels on purposely to rotate the car faster for autocross but it was very unstable at speed on the highway.

As an experiment one day just to confirm all I had thought I knew about geometry changes I purposely setup the car 1/4" below what the level I had calculated and plotted out in full scale on the shop wall and then went to and event and with everything premarked was able to change back and forth to the proper height and the lowered one and was 2 seconds faster and under far better control, feedback, etc on a 45 second course, on slicks, 1st place versus last place in class with one simple change. The car looked faster lowered but was significantly slower and harder to drive.

Carefully done one can setup a car to work very well in most all situations with very minimal changes to compensate for the surfaces, type of event and still look good, especially to those of us that understand real performance mods

Rick

 

[dyn085]

Lol

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[RAAMaudio]

Thanks Bronx

I am not on here a great deal, car is for sale as sadly just not what we need now and it will be greatly missed but not in a huge hurry to let it go either but getting to the point I need to make the change

 

[HardBoiledEgg]

God you guys take this so hard


Modifying a car makes it less reliable. As bland as that statement is; it's the same as your claim of lower offset stresses this and that. Yeah. Stuffing more air in your engine makes it more likely to blow.


These all equal out to the same picture in the end. Cause and effect. Tell the lifted jeeps and trucks they are all wrong too. Or every single modified track car that has aftermarket set of wheels. Like I said this is never ending so to say disregard my comment just cause you dont agree with it is kind of far.


This is not what this thread is about. That's why I don't want to start anything. I had a simple post.


15x9 +35 fitting under stock metal and none of this other work? Answer was no.

Am I still going to try and fit it? Yeah cause I think we don't have too many people modifying this chassis and fitting a bigger then a 8 to fit a bigger tire. Can your car be just as nice on a 8 inch? Yes but I know I'm not not the only one here who thinks a 205 (stock tire width) is tiny and we want more

 

[M-Sport fan]

Note: I only run one chassis brace on my car, DIY $2 sq tube 2 point up front, I have built full race cars, modified cars for handling since the early 70's, had the car on a lift and had a real race shop manager look over all my work and he agreed completely it was the only brace the car needed. Save your money and spend it on things to take weight off and improve handling, braking, etc....adding unneeded weight only makes the car slower even if the placebo effect feels otherwise

I fully agree with you on most of the available bracing for this car just being a weight adding, placebo effect type mod, and will continue thinking this way until someone shows me repeatable, actual digital strain gauge proof of our cars out on a road course both with and without all of the bracing (and even if the gauges do show something, it does not necessarily prove there is any actual performance benefit).

But, is your homemade bar attached like the Pierce or TB Performance underside two point bars, attached to the lower A arm pivot bolts, or something else?

 

[thePete]

My 205 Dunlop are 8.4" across the tread face. How much more surface area do you think you need in a 2700lb car? You think people are overcomplicating it, and you're drastically oversimplifying it. There is not much room for much more tire under the stock sheet metal than we have already stuffed. Anything more will require pulling the shit out of the rear fenders, or different offsets front and rear. Pulled fenders look terrible, and different offsets eliminates the possibility of tire rotations. Some guys on here have run staggered tires to cram more rubber under the front for traction. This isn't a new platform, just because it's new to you.



Edit: also, meet Raam. Ask someone else how the milk tastes and he'll give you 2 pages about why the cows in some other countries have a better product because of the grass they eat.

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[HardBoiledEgg]

Does the car need more probably not and I'm not fighting that. I want more to it. Function is great but also sunken wheels and 205 tires doesn't turn me on if your getting me


I come from my last track car being a 350Z and I was on 10.5 with 285s square and it fit that with ease. People are even putting 315 all around. Maybe this is why I want so much more out the car I'm not sure.


In the end of the day the 205/50/16 it looks like I have to run on a 4x100 16x8 +38 just doesn't do it for me but seems like I have no choice to be on the track with no rubbing

 

[thePete]

Sunken? Have you not scrolled through this thread?

... And a 350z weighs almost 1000lbs more, and is a much larger car over all. The FoST comes on 235s from the factory.... Apples and oranges.

Good luck on your quest. Be sure to post pictures.

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[HardBoiledEgg]

That's 8s and 205s?


Maybe I'm just blind to this lol cause that does not look as bad as the other threads I've been in!

 

[thePete]

15x8 pro races. 205/50R15.

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[HardBoiledEgg]

Might just need to swallow my pride and do the same


I personally will go Enkie 16x8 +38 for the sake of a bigger wheel. Next problem is finding a decent tire size in a performance tire. I really want the RS-RR again cause for bang for buck they win!


Likely will end up with the 71R or 888R

 

[BronxBomber]

Might just need to swallow my pride and do the same


I personally will go Enkie 16x8 +38 for the sake of a bigger wheel. Next problem is finding a decent tire size in a performance tire. I really want the RS-RR again cause for bang for buck they win!


Likely will end up with the 71R or 888R

Remember the treadwidth number does not come out to the same actual width of every tire. Some tires run wide for their size and some run narrow. Which is why you (or anyone) shouldn't base things relating to tires on a number. If you go on tire rack, you can browse through tons of different tires and it will give you the actual treadwidth and contact patch size for just about every tire and size they carry. I've run 4 sets of Federals for example and they run anywhere from one to two sizes wider on average. I currently run Kumhos in 215/40/17 but the federal sin the same size are about an inch wider.

 

[shouldbeasy]

That is cool you were able to fit a tire that tall and wide. I am assuming stock suspension though? Ricks is lowered on coilovers and his 225 are on 9 inch wide wheels. There's several running 225 on 8s but on 9s mods are needed in particular in the rear and when lowered.

*edit*
What brand tire are you running? Sidewall sizes can vary greatly from actual size. My 195 are as wider or wider than most 205 you see and some 225 are as narrow as some 205-215 while certain ones are more like 235-245. The type of tire can have alot to do with fit as they vary greatly in actual size vs what is on the sidewall. I think some get too caught up in sidewall sizes as in "I run such and such size..." vs actually having a wide tire in real specs (in general not meaning that towards you).

Yes, stock springs, Koni SRT.T shocks on all 4 corners.

For tires they're the Continental Extreme Contact DW which has a height of 25.0" and the overall section width is 8.9".

 

[HardBoiledEgg]

Agree on different brands being different size. My federal RS-RR 275s were wider then my previous 285s

 

[LILIKE16ST]

Yea if you run an 8 inch wheel with a nice wide 205 sticky tire I think that's more than enough to look good on these cars and perform better. If you do weight reduction like myself and others the curb weight may only be 2500-2600 sometimes less depending on how radical you go so if a 2700 lbs car doesn't need any more than this size I'm sure a 2500 lbs one will do even better. These cars handle great from the factory and don't need huge changes to do some pretty awesome things on back roads and even on tracks. I love stuffing wide tires too and I think it looks great and at the end of the day it's all about what you want as the end user....

 

[RAAMaudio]

Funny about cows in other countries
I eat butter, European or organic grass fed US. I eat beef, local raised, grass fed and finished that is incredibly tasty. I eat nearly all organic and even growing some food in our RV spot....

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Enkei RPF1 in 16x8 is only made in 4x100, had a set of those as well, I have had around 8 sets of wheels for this car and hundreds of sets over the years, at least 10 sets of RPF1, several NTO-3s like the 18x9.5 with for my track wheels and 18x10.5 for autocross wheels on a Forester XT that was far faster than most would want to believe

Again, mentioned in dozens of threads and at least a few times on this one, sidewall numbers don't mean sheat, real specs are what matters and for nearly all tires it is easy to find out.

My car is not hugely faster because it has 9" wide wheels, quicker most certainly but for the time and effort involved as well as cost I could of made the car faster in other ways much easier, part of the 9's was the challenge in making it happen, it was and is very rewarding still and as far as I know the only ST there is under stock fenders(rolled and pulled but no cutting, welding, painting, etc....)