Clever Idiot Posted September 8, 2013 Share Posted September 8, 2013 So I got this wheel/tire sizing tool from Summit so I could try and get it right the first time. It has a solid piece of #12 wire to approximate the outline of the tire along with the plastic pieces to give you diameter, width, and backspacing. I set it up for 18x9.5 with 5.5" backspacing, and used the website to get the specs for Nitto 555 285/40r18 tires (width given, did math for the sidewall). Then basically used the TLAR (that looks about right) method for turning those dimensions into how I thought the tire would behave on that wheel width. Put the frame on jack stands, removed the shocks and springs, and left the suspension connected so I could use my jack to move the rear end through its suspension travel. Mounted the tool to the wheel mounting surface on each side and put the suspension at different points to see the most possibilities. Bottom line: I have about 1/4" clearance on the inside wheel well with the "tire". The wheel clears no problem. But the tire gets closer because it's actually wider than the wheel. I did this with the stock drum brakes on, because that's what I'm going to have until I get it on the road, but eventually I'll be putting Corvette C6 disc brakes on there. I think that pushes the mounting surface out even more? Is this enough clearance? I don't know if there's a lot of lateral movement in the suspension under real world conditions, but I couldn't get it to move sideways. Well, not with putting as much force as I dared on it - it was on jack stands after all. I really like the super wide rear tire, but I don't want to cut it too close because it theoretically fits and then have it tear itself up in the actual application. I'm ok with putting 4 tires of the same size on the car, I just liked the wider rear tires. So is 1/4" clearance enough, or should I play it safer? Quote Link to comment Share on other sites More sharing options...
wallaby Posted September 8, 2013 Share Posted September 8, 2013 Ok, how about when the car is leaning in a turn? With your axle in the right place, how does your clearance look when one rear wheel is lower than the other? Remember when the car leans through a turn one side goes up, and the other side goes down. That's the motion a rear sway bar tries to control. Quote Link to comment Share on other sites More sharing options...
Malyc Posted September 8, 2013 Share Posted September 8, 2013 Not to mention that in a turn, the tread of the tire moves in and out in relation to the wheel. Probably won't be much of an issue with the Nitto, because it's a pretty stiff tire, though a 285/40 still has a respectable amount of sidewall. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted September 8, 2013 Share Posted September 8, 2013 I think you'll have clearance issues when you convert to the rear disc brakes Quote Link to comment Share on other sites More sharing options...
Clever Idiot Posted September 8, 2013 Author Share Posted September 8, 2013 Yeah, I did tilt it like it would be in a turn, but it's sooooo close. I think I'd rather play it safe with the 18x8, 4.5"BS, 255/45 that will be on the front. Thanks for the input, y'all. Quote Link to comment Share on other sites More sharing options...
Malyc Posted September 8, 2013 Share Posted September 8, 2013 You could probably go 275 wide out back and still be alright. Quote Link to comment Share on other sites More sharing options...
footballubet Posted September 8, 2013 Share Posted September 8, 2013 1/4" clearance isn't much. Especially when you have to factor all the body roll into it. I'd hate to see you rip up a sidewall or worst yet a quarter panel lip. Quote Link to comment Share on other sites More sharing options...
Clever Idiot Posted September 8, 2013 Author Share Posted September 8, 2013 1/4" clearance isn't much. Especially when you have to factor all the body roll into it. I'd hate to see you rip up a sidewall or worst yet a quarter panel lip. Exactly, Scott. The last thing I want is to push it so close that I destroy a $200 tire (or the body work that I spent a bit more than that on) the first time I go over a road that isn't perfectly flat and level, or the first time I make a turn faster than 5mph. I ordered the 18x8 wheels last night. I'm thinking for the back tires I might see what 265/50 looks like on that 8" wheel. According the Nitto website, that tire is a little more than half an inch narrower than the 285/40 I was looking at. Plus it's almost an inch and a half larger overall diameter, so it may add to the rake a bit (which I like). Quote Link to comment Share on other sites More sharing options...
downset71 Posted September 11, 2013 Share Posted September 11, 2013 I have 18x9.5 in rears with nitto 275 40s. Had airbags. Could drop into wheelwell with just a lip trim. Quote Link to comment Share on other sites More sharing options...
downset71 Posted September 11, 2013 Share Posted September 11, 2013 With disc conversion that widened footprint by like 1/8"---- Quote Link to comment Share on other sites More sharing options...
Clever Idiot Posted September 12, 2013 Author Share Posted September 12, 2013 Cool, thanks for the input. It felt a bit too tight for my tastes - I don't want to do any lip trimming or grinding for fear of messing something up. But I went out just now with the 265/50 specs on a 18x8 w/ 4.5"BS and it has plenty of clearance (theoretically). Wheels should be here tomorrow, then I'll drop by the tire shop when I can and get them put on. Woohoo!! By the way, downset71, love your car. I think it was one of your posts/car that made me look at Kore3 brakes. Pretty sure you're on their website somewhere! Quote Link to comment Share on other sites More sharing options...
downset71 Posted September 12, 2013 Share Posted September 12, 2013 Tobin is an awesome tech/owner. Helped me with multiple issues. I also converted my car to a C5 booster/ master cylinder setup and he was great helpin out with metric conversion fittings and bore size questions Quote Link to comment Share on other sites More sharing options...
Clever Idiot Posted September 23, 2013 Author Share Posted September 23, 2013 Got the tires mounted this weekend, put them on - THEY LOOK AWESOME! I have about 1/2" clearance from the outside wheel well lip to the sidewall on both sides. More room on the inside. I'm extremely happy; I don't think I could have gotten it any better, and I'm thrilled I got it on the first try. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted September 23, 2013 Share Posted September 23, 2013 no pictures....didn't happen Quote Link to comment Share on other sites More sharing options...
Clever Idiot Posted September 24, 2013 Author Share Posted September 24, 2013 no pictures....didn't happen Haha! I know, I know. I was in a hurry. Once I get some more weight on it, I know the rear will settle down a bit, and the front a lot. Right now it's nothing but the body shell with 2" drop springs on the front and cargo springs on the rear. Here we go: Quote Link to comment Share on other sites More sharing options...
Murphy Posted September 24, 2013 Share Posted September 24, 2013 Love the wheels! Who makes those and what are the specs again? Quote Link to comment Share on other sites More sharing options...
Clever Idiot Posted September 24, 2013 Author Share Posted September 24, 2013 Love the wheels! Who makes those and what are the specs again? Thanks! Boss 338, 18x8, 4.5" backspacing, 5x4.75 bolt circle (of course). Front tires are Nitto 555 255/45, rears are 265/50. I got them from Summit, since they were about the same price wherever I found them, free shipping from Summit, and it's a big company easy to get back to if there was a problem. Here's the product link. Quote Link to comment Share on other sites More sharing options...
Murphy Posted September 24, 2013 Share Posted September 24, 2013 Thanks DJ. Was expecting the front wheels to be 7"....Can't wait to see your car finished! Quote Link to comment Share on other sites More sharing options...
Clever Idiot Posted September 24, 2013 Author Share Posted September 24, 2013 You and me both! I'm doing my best to get it back on the road before June - my 10th anniversary is then, and my wife and I wanted to do another reception and drive off in it. Not sure it's going to happen, but I'm doing my damndest! Quote Link to comment Share on other sites More sharing options...
Clever Idiot Posted September 24, 2013 Author Share Posted September 24, 2013 I will say this: When the front was in the air with the new wheels and tires, I turned the wheels back and forth. Far left had the tire hit the sway bar, but not far right. I'm thinking I just need to put it back in the air, loosen the frame brackets on the sway bar and shift it more centered. Worst case, it slightly rubs just before full lock on a smooth surface. I can live with that, since I never drive full lock anyway. Quote Link to comment Share on other sites More sharing options...
cudax Posted September 25, 2013 Share Posted September 25, 2013 Love the wheels DJ, they look awesome! Mike Quote Link to comment Share on other sites More sharing options...
wallaby Posted September 25, 2013 Share Posted September 25, 2013 In this photo, the reflection of the cooler looks like a red stripe around the rim...a nice detail! Quote Link to comment Share on other sites More sharing options...
7tonemonte Posted September 25, 2013 Share Posted September 25, 2013 I love the wheels, really look great on the car Quote Link to comment Share on other sites More sharing options...
Clever Idiot Posted September 25, 2013 Author Share Posted September 25, 2013 Thanks guys! I can't wait to see how the big brakes look filling them up. They should be here soon. Quote Link to comment Share on other sites More sharing options...
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