veritech-z Posted July 19, 2006 Share Posted July 19, 2006 What's happening Hybridz? It's about time for new tires on the camo-zzzap!, and I've decided to do some searching to see if there is a better tire size than the one I'm using now. These wheels are 17X7 in the front,and I'm currently running a 205/50-17 tire. These look a little tall in comparison to the rears, so I'm thinking of going with a 215/45-17. In the back, the wheels are 17X8, and I've got a 255/50-17 which I'm happy with as far as the look is concerned. I got these tires free when a friend's dad put new tires on his porsche, and now that it's time to pay for some, I was curious if anybody had any input as far as what sizes are working for them on similar wheel widths, and if anyone had a particular tire line they were fond of. Keep in mind this is Florida, so I need an all season tread. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted July 20, 2006 Share Posted July 20, 2006 I saved the pic you have and viewed and enlarged and have a question: Are you sure you don't have 255/40/17's on the back? That would make the 205/50/17's sidewalls .05" taller each - total diameter +.1" . That is what it looks like to me - but may be an optical illusion.... 255/50/17's sidewalls would be 1" taller each than the 205/50/17 - total diameter +2", and I'm just not seeing it, once again, this could be an optical illusion. It DOES look to me that you have ~ the same sidewall height front and rear, which is why I am asking. If you DO in fact have 255/40/17 rears, then a 225/45/17 would be exactly the same height, and a 215/45/17 would provide a little rake. Quote Link to comment Share on other sites More sharing options...
veritech-z Posted July 20, 2006 Author Share Posted July 20, 2006 Well, now that it comes down to it, I'm not sure...they SHOULD be 255/40-17's if they are factory sized porsche tires, but I was almost positive they were 255/50's...The front just seems to be sitting up higher to me, and they look taller to me at least...I think in that picture, the tire pressure is a bit low in the front. The other reason I'd like a slightly wider tire in the front is so the car won't push so much into corners. Quote Link to comment Share on other sites More sharing options...
veritech-z Posted July 20, 2006 Author Share Posted July 20, 2006 Ok, so I checked it out when I got home, and sure enough, they are in fact 255/40-17's in the back. I guess I was having a blonde moment... Quote Link to comment Share on other sites More sharing options...
Forrest Posted July 20, 2006 Share Posted July 20, 2006 What offset are your rear wheels? Quote Link to comment Share on other sites More sharing options...
veritech-z Posted July 20, 2006 Author Share Posted July 20, 2006 it's really high, something like +38 if I remember correctly. I'm using 1 1/4" hub adapters all around (see my other thread: changing wheel offset...) Quote Link to comment Share on other sites More sharing options...
Bartman Posted July 20, 2006 Share Posted July 20, 2006 I'm running 225/45-17's on my car and I think they're a good choice for a 17 x 7 rim. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted July 21, 2006 Share Posted July 21, 2006 The air may be a little low, but you have a smaller tire holding up marginally more weight, so the bottom would flatten more. I took care to look at the sidewalls in the front and rear of the tire itself to avoid the possibility of this factor skewing my observation. That said, I think that if you think the fronts look too tall now, that 225's won't do it for you, because they are only .1" less in overall diameter. The 215's would be .4" shorter, and would also be a better match for the wheel for handling purposes. 7" is the minimum and usually spec'd rim width for this size/aspect ratio. I'm not sure everyone is aware of this, I may have mentioned it in the past, but will reiterate if I have: In the early 90's, Turbo Magazine was building a Mistubishi Eclipse. They had upgraded the suspension to the max and were looking at tires for the wheels they could fit. I remember vividly my surprise when on the wheels they had that the tires that the wheel was the widest spec for out-cornered the next wider size tire on the same wheel. They even did pyrometer testing across the tread width to verify the amount of traction and how much of the tread was being used, varying the air pressures for each corner as they tested. They were using 205/55/16's and 225/50/16's in the test. The smaller width tire had a more even temperature across the tread than the wider tire, which indicated that there was a lot of "squirming" going on which did not let all the rubber stay in contact with the tarmac. To get the best handling out of a tire, go with the widest rim that falls within the manufacturers' specs for the tire. You can reverse that a bit and say that given a certain size rim, what is my best choice in tire width. In a nutshell, if you are after the best traction (and you DO want to minimize push, as you stated), then the 215's would be closer to the ideal than 225's on your 7" rims. It would appear though, if one were to learn from the above real case scenario, that a 205/45/17 would provide a more stable tread and be a total of .7" shorter in overall diameter than the tires you have on the front now, giving you that bit of rake that you are also looking for. The shorter sidewalls should help controll the tread more. A few more things that you can look at, not knowing what you have done for bushings and anti-sway bars, is a little tuning in this area. Some people, in order to achieve the correct "feel" will tune the suspension by utilizing urethane bushings on the end of the car that needs to be stiffer and regular rubber bushings at the other end in order to get that last degree of "feel". If the amount of push you are experiencing is more than a bushing swap can take care of, then possibly a slightly larger rear bar... Don't forget that tire pressures are a tuning tool also. Quote Link to comment Share on other sites More sharing options...
veritech-z Posted July 21, 2006 Author Share Posted July 21, 2006 Now we're getting somewhere! I was looking all over for the recommended tire sizes for a given wheel width. You wouldn't happen to have that at your fingertips for a 17X8 as well as the 17X7, would you? As for bushings, I've only gotten as far as changing the sway bar end links front and rear, and the front mount bushings from the energy suspension complete kit. I put on the bump stops too, since when I changed the struts there were no bumpstops in evidence prior to that...I've not gotten around to doing the rest yet (the spindle pin horror stories have me spooked about those). -on a mostly un-related note, I'll be shipping those wheels to you tomorrow Brad. I'll pm you with a tracking number when I get one. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted July 21, 2006 Share Posted July 21, 2006 You can go to www.tirerack.com, do a search for a tire size, choose a manufacturer/type of tire and then once you select a certain tire you may be interested in, look at the specs page. The specs page has all kinds of info like overall diameter, tread width, load ratings, measured rim width and suggested rim widths. Quote Link to comment Share on other sites More sharing options...
veritech-z Posted July 21, 2006 Author Share Posted July 21, 2006 I discovered that today as a matter of fact. The only problem is I'm starting with a given wheel width as opposed to a given tire size, and I'd like to see what size tire would work best for that...Oh well, I guess you can't be spoon fed everything. Thanks for the heads up though. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted July 22, 2006 Share Posted July 22, 2006 Based on data amassed in the test, 205's are probably about as small as you want to go, and 7" is usually the spec'd rim width for them. Remember, the lower the aspect ratio of the tire, the narrower the rim width range that will work with it. On the other hand, there isn't as great a degree of difference between using the narrowest or widest width. I would think that the 205/45/17 would be ideal for you - you keep a good width on the front controlled well by the rim and you get some rake because they are shorter , then tune the suspension some. I really don't know what you have for power and your intended goals, so it's kinda hard to say. I am assuming daily driver/weekend warrior. Just like the 'vettes have done, a large difference in width front and rear helps in rainy weather the front tires start clearing the path for the rears and don't hydroplane as much as wider tires, they also are lighter for acceleration than wider tires. If you were going to tell me you were going to autox, then I'd say go with 16" wheels and have a bit taller sidewall - much more predictable at the edge. They also weigh less, so acceleration would be better. Personally, 16" is as big as I will go on the street or track (and I KNOW I'm missing out on some good tires) and when at a drag strip, will run 14's all around - drag fronts and slicks in back. I don't like the looks of rubber bands for tires, and they sure don't do anything for acceleration or traction (drag racing) with those short sidewalls. I look at the trend to bigger wheels like the automakers creation of the SUV market - style and image over function and ride. Too many people are willing to override common sense because the masses have been brainwashed by marketing. Sorry for the rant, but SUV's and big wheels and tires are a big gripe for me - I had a resaurant in the 'hood here in Atlanta and saw people with little money buying SUV's and putting on (expensive/stupid) big wheels and tires and not be able to afford gas for them, or to feed their kids. Quote Link to comment Share on other sites More sharing options...
veritech-z Posted July 22, 2006 Author Share Posted July 22, 2006 Right behind you Brad, I worked at an Advance Auto parts in Thonotasassa, and I had a conversation with a guy driving a 4 year old Lexus GS300 painted metallic candy pumpkin sitting on 18" chrome wheels that didn't have three dollars to get gas that night. I always said I'd never go larger than +2 on a z, but I got such a sweet deal on these wheels, and for all intents and purposes, they are the only set of them I'm likely to see anywhere else (girl in a prom dress syndrome). I feel that it's ok to give up ultimate balls to the wall performance for a small amount of style on a street car, considering that it's primary duty is not going to be racing. I have a set of 15X7 MOMO quasars that I was planning to put a serious performance tire on for those times that I was going to have some real fun with the car, but if anybody wants them, I'd part with them in a heartbeat. I'm still holding out for some 15X8" Advan Oni's to fall in my lap, but I really doubt that will happen...I keep waiting for the point of diminishing returns with SUV's and their "wheels", but it doesn't seem to have reached that critical threshold yet. I think the "spinners" are the single dumbest thing invented for a vehicle since the undercar neon light. I'm very particular about wheels, moreso than any other exterior mod, and I only like certain types. Definitely the auto equivalent of a sneaker pimp. I constantly argue with people around me about not buying oversize chrome wheels for their cars, but I can only cry out in the wilderness so many times before I just start saying "sure, if those are what you really want.." I've come to the conclusion people ask my opinion AFTER they've already made up their minds because they already know I'm not going to tell them what they want to hear. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted July 22, 2006 Share Posted July 22, 2006 It took me a year, but I convinced my brother-in-law to lose the 22" wheels that came on his Navigator via the previous owner. I think the $280 a tire had more to do with it, but I kept telling him that he'd get better city mileage and much better ride, brake better and lose a bit of quick steering response and only have to pay 1/2 for good Michelins (the only tire made in the size he needed was Nitto). I found 4 take-offs with 18K on the Michelins for $485 shipped and he just put them on yesterday and took a trip today out of town. He was very pleased. He sold the stuff he took off for $3000, which put him in a good mood too. Quote Link to comment Share on other sites More sharing options...
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