As per the title, anyone know? I'll be using the standard Sport size alloy 16X7 ET37.
Thanks in advance.
J.
JJJ.
You can go a 25mm max if the suspension if the car is low and suspension is rigid, I would safely suggest 20mm. I have a 9.5" wheel on the back of mine with a 30mm offset and a 245-35-18 wheel which is a little bit tucked sidewall. Here is a comparison of yours and mine. You will see the charts says you can go 27mm if using a 205-55-16 tire.
Cheers Vetruck, that sort of confirms what I was thinking. Next question, is it worth the bother fitting the spacers, the only reason I'm going to do it is the car tends have a wide front track compared to the rear. Generally speaking, will I gain or lose anything just increasing the front track by 20mm & the rear 40mm, what do you think? Currently I'm using Sport wheels 16x7 (05/55/16's), Sport springs and adjustable shocks.
JJJ.
Generally you will loose overall handling ability of a car unless the suspension is balance for such changes using roll center changes with the proper balance of spring rates, shock rates, and fine tuned with sway bar changes. Most cars with wide rear tracks have done so in order to get enough tire back there to handle large HP race engines where inboard increase of wheel centerline is also widened. This forces a wider footprint from that wheel in a forward direction of the vehicle into the center of gravity (cog) of the car. Basically in laymans terms, think if one rear wheel was driving power(lets say the right rear) and the other left side wheel broke the link of power transmission and was passive- the car would want to steer left..... Thus under throttle a wider track on any car would make for a little more squirrely ride under "high HP" situations when pertained to grip- we do not have anywhere near those power levels, most street vehicles do not.
HOWEVER, in the oppsite fashion- under braking? It does make a difference in handling. The more traction you have under braking force (most cars can stop very fast if given good performance tires) an imbalace in traction surface can wander a car under braking. THis is still not the most delicate problem but I am getting there with explinations of these two straight line characteristics first. The rear wheel with more surface grip can yaw the nose of the car to pivot in that direction on simple physics. The further it is out the more previlent the effect.
Now here's the real issue. With the understanding of how it is effected in straight line power application AND straight line braking application with a push & pull trait on the cog (center of gravity) you now brake hard as setting into a corner (lets again say to the left). the RR wheel sits 1" outward of the RF wheel in straight line tracking- the car will want to tighten and not turn/rotate as easily to the left under hard braking turning diue to the RR being outside the RF in path. The reverse goes for throttle application (but again we do nto have nearly enough power in throotle as we do under braking force) so the car will go loose (rear step outward) under power because they do not follow the same path.
Take my car for an example. I run a much fatter rear tire/footprint then I do the front- however my track path of the outside sidewalls of both front and rear tires take the same path because the rear tire exceeds inward towards the car's centerline more then the front does. What this does is makes the car a little more loose under braking entrance then it did prior, and tighened it a little on power exits.
Always best to line up the outside tire sidewalls int he same path. These cars (like most street cars) are not designed for ulitmate performance handling so every little bit helps to take out the notorious tight corner entrance-into- snap oversteer to get them to try and rotate into and through a corner. Stepping out the rear track only to be wider then the front will onluy make the car more tight resulting in a slightly harder to rotate vehicle under hard braking.
Last edited by Vetruck; 01-27-2015 at 08:20 AM.
Thanks for that information. To be honest, I hvae never considered the affect of having different width stances and how it changes handling.
Great stuff!
Vetruck, thanks for your comments. So, another question just to clarify if you don't mind. Is it advantageous/worthwhile getting the rear track width closer to the front track width?
For example, a basic W202 (195/65/15) the front track is 1499 mm & rear 1464 mm, making the front wider by 35 mm. Should I aim for increasing the rear track by 35 mm?
The reason for all my questions is that I understand the general guide used for track width to wheelbase length is 0.62. The wheelbase in this case is 2690 mm x 0.62 = 1662 mm track. So, the closer I can get to that figure the better, not that I'll get very close as the difference between 1662 mm and current tracks is massive. Just thinking ever little helps, even if only an extra 35mm on the rear????
JJJ.
As for over wheelbase vs trackwidth?That gets into a more technical novel...lol. Making a track width wider WITHOUT moving the suspension geometry points further off centerline of the vehicle will only increase leverage on the spring rates (which in turn makes the car roll side to side easier. That is why these cars do not corner well. They are long narrow and tall making them a real challenge.Originally Posted by John Jones Jr.
Now to what we actually have- Most race cars in the world (I would dare to say 70% of regulated series) all have equal or more front track width then they do rear track width.
Why?
This increases ability to turn into a corner (as I stated in my first post) as well as having the rear wheels closer together increases there ability to retain traction better on both wheels. Since these cars roll easily (pitch, roll, yaw) the wider a rear track with the narrow platform (narrow suspension points) would only reduce the amount of equal grip on both rear tires. This is factored into a car for safety in engineering design.
I would recommend putting the outside edges of the tires equal distance from centerline of the vehicle, but never have the rear outward more unless they are also inward more too. My car for example has 8.5 fronts and 9.5 rear wheels. The rear wheels basically sit inward 1" more- in other words, if you were to measure from inside edge of the rear tires compared to inside edges of the front tires the rears would be aprox 2" less apart. they are closer together for added traction at all times. Note that if they touched then they would act almost as if they were the same tire even though they are separate.
Yes I would space it out the 35mm only because I like the looks of the car with even fender lips looking front to rear downt he side of the car.
Lets go further into my NASCAR settings. Of course with circle track racing we go left turns. My rules allow me to have a 70" front track and a 69" rear track. I put the right sides directly stringed in line with path- that puts the LF sitting outward to the left 1 whole inch more then the LR. Think about grabbing a pole with your left arm as you pass it- with your arm extended parallel to the ground it will grab the pole and pull you to the left circular. The further out there it is the better it will rotate you. That front left tire is out there for that reason. The rights stay in path for chassis balance in handling/lateral grip, the left front is what steers you. The LR is tighter in track width to keep heat into the tire as not to transfer as much motion over to the RR -OR the the RF diagonally upon banked compression entrance. I am starting to get deep into stuff that does not matter like added cross percentages and wheel stagger but they play a combined role in what we seek to acheive in that sport. Does not apply here other then to say a widred footprint from LR to RF is not always more stability, there is other harmful effects (same as for pushing out wheels with spacers too far to increase track width at a harmful effect of increasing roll leverage {and wheel motion rate decrease} on springs and swaybars.)
You guys are getting me started...lol. Your heads will hurt.
Now if I wanted to play with the NASCAR truck reaend and move it to the left 1/4" it will definitely make a noticible difference in handling. The car will get a little looser on turn in, and tighten up on corner exit. Problem is we already have that probelm with these chassis and fight to go the other way (ie- tighten them in and loosen them out) once we have mid-corner "Steady state" balanced well. Moving this in or out would throw off steady state balance just to improve corner entrance or exit. Touching track widths to an unequal outside edge is a bandaid fix in my book. I try not to do it ever.
Last edited by Vetruck; 01-27-2015 at 09:03 PM.
O.k. so, I'll leave the car the way it is because I really don't want to do anything to the chassis or suspension without actually gaining technically.
Thanks again Vetruck
JJJ.
I run 9.5s on the front and it made a big difference in handling, I have 21mm spacers and 9mm spacers on the front.
Can you please post side and front fender views of this so others can reference you claim as viable or not? Reason I ask is you can put 12" wheels on the car and it will fit, but will stick way out past the fenderwells and rub at full lock.
Thank you.
Ps- in my case, I know for a fact that 9.5s would not fit on the front of my lowered 94.
Last edited by Vetruck; 03-16-2015 at 11:52 AM.
I want to thank you for posting pictures. Everyone here has there own opinions as to what "looks good" and what "Does not look good".- This post is not about that. What this post is about is whether or not a 9.5" rim will PROPERLY fit on the front end of a W202 so as to inform anyone in the future who may read this as to a purchase choice based on facts.
The idea that you were able to fit them onto the car is a mute point, The fact is they DO stick well past the fender lip and with adequate wheel travel they will in fact hit the fenders it the proper sized tire were installed on those wheels- Not a stretched undersized tire. You like somewhat the stance look. That is fine. This post and thee pictures are VERY HELPFUL to someone looking to do the same. HOWEVER- as for someone wanting a wheel that fits the fender with a proper tire size and proper geometry, you photo proves that a 9.5 wheel does NOT "properly fit" the front of a 202 for 1) proper geometry of suspension for good tire wear, 2) proper suspension travel without rubbing, and 3) it does not vertically tuck inside the fender lip (yet, in fact the rim lip sticks out quite a bit further then he body and is clearly visible when your picture is zoom upon).
This post is not intended to embarrass anyone, my intention is to stick with facts so people do not make a purchase and later find out your claim not to be true and they wasted their money on a wheel that is not proper.
Thank you. Dean
Last edited by Vetruck; 03-17-2015 at 10:47 PM.
What this post is about is you wanting to be a know it all. How about actually trying different offsets, wheel size, and tire combinations. I've had over 11 different sets of wheels on all three cars, I've also tried eibach, vogtland, KW and H&R spring combinations, all on bilstein sport shocks. How much real world testing have you done? Oh, and the two other cars are stock so don't come here and claim I'm into the "stance scene". One of them has 64k miles and will stay untouched and original.
1. Technically the proper size for a 18x9.5 is 265/35-18, but no one would ever want to run this size on the front. You stated you run a 245/35-18 on the rear which is the incorrect size for a 18x9.5 and the sidewall is not vertical to the wheel (it's stretched). Also it's the incorrect diameter for the w202, you should always stay close to the oem diameter. Your tires are undersized, which is coming from someone talking about "proper sizes".
2. If you understand the geometry of the Mercedes suspension you would know the wheels will naturally camber in and TUCK under the fenders with suspension travel. Like I said, I don't rub even when the car is loaded with 4 people in the car. Ill post a picture of the car fully loaded with the lip tucking under the fender if you want.
2. You have no idea how long I've had this set up. I've had 1 set of tires in the last 3 years. Tire wear is mostly due toe, Not camber. The car is not slammed, it's only lowered 2.5" on the front and has 4-5" clearance on the front bumper from the ground, camber is -2.9
3. Fitment on these cars has to do with offset, most generic offsets are too high or too low. You'll either buy wheels in the +35 and up range or get into the low 20s. You can fit larger tires and wheels with simple modifications and the correct offset, these are the FACTS even with the proper tire size. Go ahead write another essay about what "proper size" is according to you. We're not talking about NASCAR trucks here.
Here's another pic with a different staggered setup, I hope I don't get embarrassed by your knowledge. These are on 225/40-18 and 255/35-18 which is the correct sizing for the w202.
Last edited by c230; 03-18-2015 at 06:04 AM.
I was choosen to be a moderator of this forum solely because my vast knowledge of chassis dynamics. I am not here for a pissing match, I do happen to know it all- I am a paid professional in that field and of course is my job to fully understand chassis dynamics.
The tire I run on my rear 18x9.5 is not undersized for the wheel. It is a 245-35-18 and is designed for proper fitment on an 8-9.5" range of rim width. My front is a 215-40-18 on an 8.5" wheel. This front tire is designed for a 7-8.5" range of rim fitment. Both of my tire fitments are proper as designed by the manufacturer and are both 24.8" in diameter which makes the car 0.1" lower that factory and picks up only .03% of gear ratio. I would hardly say mine are not a "Proper fitment".
To the point of you alignment and chassis effects- You are running a static -2.9 camber (Again I will say static) in dynamic form, can you tell me where your tire contact patch is and how much body roll in degrees your chassis is producing? Your footprint is hardly optimum. I will tell you bluntly mine is perfect. My lateral and braking grip will run circles around your car performance wise. My tire wear will be even unlike your and will out last your improper tire wear. On the point of drivability= we both know your car wanders all over the road and you fight the steering wheel with every rut in the road you encounter., You will claim 3 years of tire life- claims are like opinions or also like body parts, we all have them. I hold this suspension forum to facts. It is how and why I moderate here is to keep information perfect so others reading this can base purchases on (info used to spend hard earned money on and not waste it on advanced expensive tire wear or rubbing issues). You have the choice to run what you want, I am not knocking that. I will however caution you in challenging my character that its my way or nothing. It is the correct way, not my way. there is only one correct way to set a car for safety and longevity= proper geometry.
The last point I will make is SAI and scrub radius. I will give you a chance to explain these issues on your car before I go any further. THese both create big problems on your car with those wheels sticking way out as they do in performance. I will give you time to explain. THen later this "know it all" will actually explain to you or anyone else reading as to what those problems are and why they can not be corrected on your suspension geometry.
The microphone is passed to you- please keep it civil or your post will be deleted.
Last edited by Vetruck; 03-18-2015 at 08:13 AM.
I will also remind 230 that the original topic of this post by JJJr was to ask what the largest wheel spacer one could use on the REAR of his car. He was asking for a certain wheel size and putting it out as far as possible without having to rub or modify his vehicle to make clearance.
Your above quote was on a post about rear fitment. you posted about front wheels and gave a front and rear spacer width with no rear wheel size. That was in no way helpful complete knowledge to this thread topic. Instead of censoring/deleting the post, I opt to give people a voice- yet in doing so, I ask you to post facts in order to help this forum and advance knowledge so people have facts. it was your choice to post this info- to come into here like you are a "Know It All" and that you have done something that no one else has figured out. So again I say, the microphone is yours and please keep it civil debate/discussion as to how and why your "made a big difference in handling" What is that difference? Please post facts. I am not a moderator that will censor other that attacks on personal character.
Since you did in fact attack my character with the know it all statement, I will EXPECT your next post to include the answers to my questions responding to you verbal attack.
1) SAI and included angle- What is your car doing?
2) scrub- radius What is your car doing?
3) what is the big difference in handling?
My next response here will be to also address wheel bearing issues.
Last edited by Vetruck; 03-18-2015 at 08:41 AM.
turn it down a bit guys.....
Now that you deleted my reply I see that the point of this section is for you to use it as your personal Q/A.
Here's a quote from another member..
Last edited by c230; 03-18-2015 at 10:12 AM.
I use facts and resume to explain to people that do not know me the level knowledge that comes from myself is credible. I ask you do the same. You are again avoiding the questions and have resorted once again to slander.- this has nothing to do with this post.
I could simply delete this and ban you since you have already been warned. What I prefer to do is keep to topic for the benefit of anyone reading this for information thus I will continue to give you a voice-WHY? Because I would like you to defend your position with mature debate and facts to back the claim you made in your first post. I will leave this response because it is only an embarrassment to your actions.
Now in fairness, you posted a comment as to 9.5s fitting the front and it handles better now. I then asked a question in response to that about said, etc. I would appreciate and expect you to keep with this discussion you started and back yourself with facts, not slanders.
Dean
Now please continue the debate and answer my 3 questions as I have responded to yours.
Last edited by Vetruck; 03-18-2015 at 12:38 PM.
so those spacers......
What is it you are a asking or contributing about spacers?
Like I've said, you've never asked me about offsets or tire sizes, how can you have a credible conversation about suspension geometry without these numbers. I've read through other post and you keep doing the same thing to other people. I'm not going to entertain your essay writing and how you feel you're the expert. You are welcome to ban me or delete the thread, it's not going to change the fact that you will run people out of this forum with 10 or less active members now.
I've given adequate time for 230 to respond to my questions to him as to how an why his car has a "Big difference in handling" when he installed the 9.5" wheels up front on a w202. Let me address the 3 questions and explain why there is a problem.
When you put a wider wheel on a car, there is what is called SAI (Steering Angle Inclination) built into the OEM geometry of a vehicle chassis platform. This is an engineered setting based on the wheelbase, trackwidth, steering box geometry and pressures, and overall Ackerman angles of the car. It has an effect as to how the car turns and how the car tracks in stability in both low speed and high speed. It effects how the car brakes in a straight line, it basically is EXTREMELY important to a proper handling car. Changing this will change the needed alignment of any vehicle. Its one of those things that is very rarely understood and most commonly overlooked due to lack of knowledge. Yes I am about to write a novel- not happy about it- but with the existing debate I feel it is necessary to explain to all what the hell I am talking about and what exactly all this is about. So here is why a 9.5" wheel is NOT proper on the front of a W202 even though you may THINK you can make I fit.
1) SAI is the angle of the steering "swing". The best analogy I can give to this is think of a golf club. Each person holds a golf club differently - hence the reason each person needs to be custom fit to a golf club angle and club face. Some people may have a natural swing with the club shaft at 14* from vertical, others may have 10*, yet again some one may have 20*. What ever that angle of club shaft, the club face needs to be parallel to the ground (Think of the club face as the spindle). The shaft angle is an imaginary line drawn from the upper ball joint pivot ball- down through- the lower ball joint pivot ball. Now that imaginary line extends downward to the ground. Where it hits the ground is very important as to how it matches with the tire contact patch. On a rear wheel drive car with modern power steering, you want it very close to the centerline of the overall tire width (with a slightly positive scrub radius.- this means the line hits the ground inside the centerline of the tire more towards the center of the car.) The less power steering on a car the more the need to move this more positive....
...which leads to massive scrub radius. Years ago, In order for the little old lady to turn a car to full lock to get into a parking stall, the steering wheel was had to move with a neutral scrub radius. Engineers had to move it positive in order to allow the wheel to rotate around the SAI pivot point and steering took less effort...BUT AT A PRICE. That price was the suffering of straight line braking. The more the wheel moves off center of the SAI, the more the car will wander upon braking and the more the steering wheel will want to rip out of your hand. Now to one point- Question #2 Scrub Radius. When the 9.5" wheel goes on the car, the centerline of the wheel moves outward 1.5" more positive from SAI That is huge. This puts pressure on the inner and outer wheel bearings and will prematurely wear them out due to not being centered on the hub spindle in pressure.(try to walk with someone putting 20 lbs of weight on your right shoulder only- yes your spine is your wheel bearing in this case.) Under braking, the car will jolt from side to side as the car hits imperfect road surface (All roads are imperfect, some worse then others) When you combine included angle to this you have a footprint that sometimes touches the outside edge on one side of the car and the inside edge of the other side. Yes this yanks the car side to side and you fight the steering wheel. Handling is a big difference? You bet! In a terrible way. Massive positive scrub radius also makes for a car hard to pinpoint through an apex due to a squirming tire contact patch because SAI leverage is increased and moving about making it unstable. I hope a lot of you are visualizing this. I understand it is hard to- Ive been dealing with this stuff my entire life. It is something very few people in this world ever fully grasp.
I will go on- Back to the golf club senerio. Think now you have a 12* golf club shaft (SAI) and cub face parallel to the ground (0* camber on the wheel). SAI is pretty much as effective on the chassis as CASTER is. They both work in tandem. I will repeat- THEY BOTH WORK IN TANDEM. The more SAI, the less caster. The less SAI, the more caster. When you change the footprint centerline of the tire? You screw up all of this....and more. When you rotate that club shaft as if you are turning the left wheel to turn right= the club face will go into the ground at 0* caster. It will go into the ground just the same to the left with 0* caster. WHy, the 12* angle will make it force downward as you try and rotate it 180* This lifts the car chassis. Now when you combine lets say 8* positive caster (you lean the golf club shaft towards the rear of the car) the left turn goes into the ground very hard, the right turn almost stays level.
>>>NOW ALL THE WHILE I AM TALKING ABOUT THIS, WE ARE MERELY THINKING THIS IN STATIC . IT DOES NOT STAY IN STATIC FORM. EVERYTHING IS WORKING IN DYNAMIC MOTION AND ALWAYS CHANGING WITH SUSPENSION TRAVEL<<<<<<
...So, When we consider dynamic motion of the suspension, the caster may gain to 13*. This in a 12* SAI would be optimum in order to slightly lift the outside wheel and maintain a camber gain through steering angle in dynamic braking forces upon the tire contact patch. (I know, Your heads hurt. I'm Sorry- Remember, this is my field of specialty for many many years. not something you will learn from this simple novel). So now to bring this all in with the higher positive scrub of the 9.5" wheel? It will lift the inside edge of the chassis in a tight corner and roll the car in attitude much more violently BECAUSE the wheel swings in a greater arch. As it does, the car will bobble back and forth on th inside and outside footprints because the SAI increase instability in distance from SAI. Ever notice a car at full lock in a parking lot seems like both front tires are fighting each other? Yes this is because often of too much scrub radius. Mostly happens when someone modifies a car suspension and messes up the geometry (99.9% of people modifying cars. Even most racers do not understand this- You would be amazed!!!) Rule books are in place for reasons like wheel bearing malfunction prevention to keep people from hurting themselves on a race track.
Im going to stop this for now. I think hopefully most of you will start to realize why I asked 230 to please back the claims he made. he did not realize there is someone like me on here that can see right through his bullshit. It is not arrogance, It is experience and knowledge. Please understand I am here to help each and every one of you with questions. I do this for free. I have no agenda other then I like teaching and helping others do things the correct way through education.
Thank You, Dean
EDIT: I want to add that if any of this intrigues anyone then please feel free to ask on any particular- I can elaborate in much greater detail if there is anything in this you want me to clarify better. I merely brush over some basic general facts so you hopefully understand there is a lot to this - more then most people ever know in a lifetime. I have been teaching this for 2 decades.
Last edited by Vetruck; 03-18-2015 at 09:54 PM.
You are finished here with your ignorance. I already know what the minimum offset clearance is next to the upright.
A 9.5" wheel up front is improper. Do it for looks if you so desire but understand the performance loss and reliability loss over the years.
You camber you tire so much not to hit the fender up top, so what's the point of putting a 9.5" wheel on the car when you are only able to ride on the inner 4" of tread? But you are too ignorant and keep begging me to embarrass you with facts.
Thread closed.
Last edited by Vetruck; 03-19-2015 at 02:32 PM.
Info complete for op. Thread closed.
Posting Permissions
