i have actually said this before brad...... matter of fact, i am pretty sure it was to rick i was saying it!!! hahahahaha someone would be very hard pressed to fit a 315 in the back on a car that sits as low as mine or even ricks. just not enough room inside when the wheel is widened to the inside like the ones you and i have from weld craft. you could probably try running a 10mm spacer so as to not have to do any metal clearancing, but a spacer that thick would require replacement of the studs for sure!!! you would also want to have a machined spacer that truly fits the hub correctly as well. i am currently working with dan at billet tech on doing some machined spacers. btw, do you still have those shots of your car with the 315's on it??? just for people to reference.
I know turd....I was just looking for a second opinion! My dilemma is that I want to continue to run the Vredestein's on the stock 20" wheels. I'm happy with the 275's but think I'll need a little more meat on the back when I do a power adder later this year.
I can say that after I added the 315's I noticed a huge difference in traction, matter of fact the car hooked up in places where it was easy to break them loose before. I have had the Yokahama Advan ST's on my car for 20,000 plus miles now and since they are staggered sizes, I havent been able to rotate them. They are wearing the best of any tires I have ever had, on any car that I have ever owned. I know they are the dreaded SUV rated tires, but I noticed no increase on tire noise when they are new and they are still the same now. I know there are more options out there now in the 275/315, 20" inch rim size but when it comes time to buy new meat, I am staying with the Yok's........ P.S. It is a cool feeling to know when I pass a fellow SRT8 owner on the road, that he is probably wondering how the hell I got the tires to fit in there~~:shifty: P.S.S. Chris isn't so much of a TURD as he is a LOG!!
It's a miracle! I've asked this before... No doubt a wider wheel and tire on the rear will give you more straight line traction. That's great for the drag strip. I've got to wonder what this does to the suspension geometry for the road coarse? How much of a stagger can you go with before it can't be compensated for with suspension adjustment?
My feeling is that whatever clearancing you will have to do to get the wider tire in there you will also have to be concerned with even more clearancing for the side to side movement when on the road coarse. With me, it didn't matter because firstly my car isn't lowered and secondly I don't road course race. I think that to go wider than Chris's (Legmaker) tire size of 295 in the rear would have to mean that you are sticking with straight lines and staying out of the corners. Besides too much rubber is going to probably give you diminishing returns on the road course the wider you get, anyway. Either you do that or you but another set of SRT rims, widen two to keep, widen two to sell and swap rim/tire combos when you drag or road course race......
I don't know...but I would think that wider in the rear isn't all that bad for handling. Vettes and Vipers have pretty wide tires and they seem to handle alright!
But that was a requirement/assumption for the original suspension design/geometry. They started with that and then designed/developed the suspension for or around that. I'm not saying that a significantly larger stagger is better or worse by itself. Just that it seems to me to be a fundamental change in the suspension geometry that would have to be accounted for. What and how (or even if it could be with our suspensions) I don't know.
I made sure that I bought a tire that was as close to original diameter as the F1's that I took off. Matter of fact they were within .1 of an inch...i dont know that the geometry of the suspension has changed, only the forces from the extra traction....I am sure there are other variables, but I am not an autocross champion....
I was using the term "geometry" loosly to include EVERYTHING. Traction, force vectors, travel, angles, width, where the contact area is in relation to the center of gravity, ...everything. Sorry for the confusion.
i wonder what your thoughts are dave on the rear end suspension being afftected by wider tires and the traction aspect of things. wider tire, bigger contact patch, better traction, more sideways force being put on things like springs, bushings, etc. wouldn't you think the sideways type force angles coming from increased speeds/traction could adversely effect the handling??? like you mentioned earlier, other cars with good handling and staggered set ups were designed that way. how much adverse effect, if any, could come from changing a car, especially one as heavy as the charger, with increased rear traction???
Well... I really have no idea. I am under the impression that all parts of a suspension are extremely interdependent on each other and significantly changing one part or another can significantly effect the system as a whole. Adding traction to the rear is one thing. But all the angles and travels are by design also. For example if, when you widen your tires it extends them outwards at all, then you've effectively increased the length of the control arms and reduced the curvature of the arc they travel as the wheel moves up and down. That sort of thing. What effect, how much effect, and if it's good or bad I really don't know. just one of those things that makes me go "hmm". :grin:
Dave, Please read and interpret. I think YOU will appreciate the level of discussion these guys are having on this forum. I copied a few posts that made some sense to me. http://www.eng-tips.com/viewthread.cfm?qid=102250&page=1 "When going to a wider tire and assuming that the contact patch is now wider (but shorter in the longitudinal direction -- assume same inflation pressure and load in each case hence we end up with same contact patch area), it would seem that the benefit could also be coming from the distribution of the cornering load across the contact patch as it relates to the distance from the leading edge of the patch? I'm trying to build a mental image of how dramatically different the contact patch to road interface looks between two different width tires. For example, consider a 205mm tire versus a 275mm tire both with the same sidewall heights. At their respective limits of adhesion under cornering, there would seem to be a dramatic difference in that load (and slip) distribution on the contact patch. Is there any source for further information on this subject?" "I believe a strong case can be made that with a standard OEM suspension the handling will become worse as you go wider as the camber curve will drastically alter the contact patch."
Haven't read it yet. Going to right after this. Right and wrong. If you go to a wider tire you WOULD/SHOULD run them at a lower pressure. Just for the reasons he stated. Same load being supported by a wider tire. The tire was designed for, and should be run so the tread lays evenly on the road side to side. Lighter car will take less pressure with the same tire and the same car will take less pressure with a wider tire. If the tire is inflated properly a wider tire WILL have a larger contact patch. I think he's speculating a bit too much here. If everything is increased proportionally, car, tire, weight, dimensions, etc. it will just look bigger. If only the tire width is increases there will just be less distortion at the threshold. Since the force per square inch pressing the tire to the road will be less as you increase the tire width the increase in traction will not be directly proportional to the increase in tire patch area. that's all. I don't think so much. It would be effected by the extra width being added to the inside or outside of the existing tire. The camber curve would not change if you added width on both sides of center equally. Ok. Always more fun to comment from pure BS and speculation before going off to read the material :happy:. I'll go read now.
Ok, read that. Amazing how forum discussions are basically the same everywhere. They started out with a question. There was some basic speculation, then a few people came in with a boatload of unrelated but parallel stuff and a few more with extraneous crap and about 2 of them actually knew what they were talking about :grin: (knap and ubrben - you can probably take ubrben's speculations to the bank). Summary: wider is better. to some point relative to what your suspension can handle or be adjusted to. Note that no one addressed the effects of stagger (which is mainly what I was wondering about). Also note that no one on there was a suspension tuning expert. What they're talking about is: Coefficient of friction * normal force -- this is how friction increases as you press down on something. Two materials will have a coefficient of friction. The amount of friction between these two will be a product of that and how hard they're pressed together. The weight of the car and other forces like braking transfering downward force to the front tires, etc. Material deformation over the road surface at the localized level -- That's friction caused by the tread compound molding to the (rough) surface of the road. Sticky tires give you more grip. Think of pressing silly putty on the road and then trying to slide it sideways with no down force on it at all. (they also refer to it as local deformation). Global deformation -- this is where they're talking about the shape of the contact patch deforming with lateral force being applied to the wheel/tire. Also slip angle (see below). Greatly effected by lateral stiffness of the sidewalls. Radials helped a whole lot in this department. Can't believe that guy jumped in there for a few posts to compare wider BIAS ply tires to narrower RADIAL tires... sheesh (in case you're wondering, the radials won). Slip angle -- the difference between where the wheel is pointed and where the contact patch, or tire, is "pointed". As more weight is transfered from the inside tire to the outside tire the slip angle tends to increase. Not a lot to do with what we're talking about. They were mostly talking about what is the dominant factor. Coef of friction * force vs. length of the contact patch side to side (surface area). Is it better to have a 10lb weight sitting on a 10" strip of rubber (1lb per inch) or a 1 inch strip of rubber (10lb per inch) when you go around a corner. Seems that it's better to have the 10lbs on a 10" strip. Great. We kind of figured that since slicks are better without grooves in them. So maybe it's not just a marketing scam by the big corporations to get more $$ by making you think bigger, fatter, sexy looking tires are better than skinny bicycle tires like a couple of those guys were thinking. So that is one component. They didn't get into suspension changes that might take advantage of or or be necessary for wider tires and stuff like the effect of moving the center of the contact patch further out or in from where the suspension is designed or set for. They didn't talk about stagger and the effects on handling or suspension changes for that. I'm hoping some of you road racers know some suspension gurus to ask. Can email one of your instructors Rick? Surely one of them doesn't hate you :grin:
