New wheels!

[speedracer25f]

Ok, so they are just speedline wheels, but they make a huge difference over the aluminum 16" that were on there.

[02transamce]

Looks very good!
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[Baluchitherium]

Much improvement has been made young one...

[silverWS6]

I love those wheels on our cars, and i wanna buy a set later on when i have some extra cash

[Schmalgar]

I love those wheels on our cars

+1. I think they're the best of the stock rims on 4th gens...

[WS6S]

plus 2

[speedracer25f]

Can someone with a factory ws6 tell me what the car recommends on the sticker for air in these tires? My sticker says 30lbs each, but that was for the 16x8s. Im thinking maybe these should be different.

[TmaxicanA]

with my speedlines i ran 30 in the front 28 in the back

i know its not factory specs, but just my 2cents

at first i hated my speedlines, then i wrecked the car and destroyed 3 out of 4 and...funny you dont know what you have till its gone lol

[Schmalgar]

On my WS6 it says 30 psi for each also...

[Cutlass]

my WS6 also says 30 psi all 4 corners.

[basballny2]

i do em with 32-30

[JWSmythe]

I run 45psi in mine. The tires say max pressure 51psi. I check the tires hot, so I know they're lower when it's been sitting. I really need to get an infrared pyrometer to set them right.

There's a whole art to setting your tire pressures. The number the manufacturer gives is just a good safe number for the daily driver. Read up on how race cars are measured. We won't be probing through the tread like race cars do, so surface temperatures will have to do.

Pressures really have to be set for the vehicle *AND* the tire. The guideline on the car just isn't good enough if you want the best performance, fuel economy, and tire life, even if you're using the stock tires on an unmodified vehicle. Since I don't think any of us are bone stock with the factory stock tires, we have to measure to get things right.

You can pick up a laser guided infrared pyrometer online pretty cheap.

Basically, you measure the inner, center, and outer temperatures. That is about 1.5" from the sides, and one measurement dead center. You'll want to keep a notebook handy, and write down all your measurements (all 12 tire temperatures, the ambient air temperature, and pressure when the measurement was taken). You'll end up writing down an awful lot of numbers until you get everything just right. You'll also want to take the temperatures when the tires are hot (like a long run on an Interstate), and take the temperatures as soon as you safely can, as the tires will cool as you drive slower. A gas station right at the offramp is much better than one a mile down the road.

An underinflated tire will read colder in the middle.

An overinflated tire will read hotter in the middle.

An alignment problem will show as one side is hotter than the other. For serious racing, the alignment is adjusted for each track. For example, circle track racers may give more camber on a longer track with faster turns. They also frequently use smaller tires on the left, to help them turn aggressively at speed. Since we turn both ways, we won't be encountering that. Autocross and street track racers will want to set their camber for the average turns they encounter, but may adjust to give better traction on a difficult turn and sacrifice traction on easier turns. Drag racing may want to have overinflated tires in the front, to reduce friction, since they aren't steering too much, but they definitely want the perfect pressure in the rear for maximum traction.

Variation in tire temperature shows as wear along the life of the tire. For example, overinflated tires contact more in the middle, which is why the middle gets hotter, and that will wear faster. If you're looking to keep your tires for a while, it's better to know how the tires are reacting now, versus 50% into their life. Differences in wear frequently isn't obvious until the tires are well through their life.

Always use the same pressure gauge and pyrometer, so you know your results will be consistent. If you use the gauge at the gas station air pump, it could be several PSI different than the gauge at another gas station. Your target pressure is within 2psi of what you measure to be absolutely correct. My digital pressure gauge has a 0.5psi resolution, which has been "good enough". Since I just gave it away, I'll get a better gauge.

I've been using the same brand and series tires for a while. 3 sets of one series. The most recent is the same brand, but a slightly cheaper tire, since I was short on cash. Running them through their life, at 45psi they've worn equally. The front tires get a little extra wear on the outside from hard cornering. Just because an onramp has a caution sign for 45mph doesn't mean I won't do 70mph around it. I want to be at merging speed. I don't want to enter fast traffic under their speed. Around here, when I hit an Interstate, traffic is usually at 75mph to 85mph, which is a lot easier to adjust to from 70mph than from 45mph.

Most of my tires have been changed because of casualties to road debris or my own stupidity. Like, I tore out a sidewall on a front tire loading my car onto a narrow trailer.

[Schmalgar]

A bunch of stuff, only half of which I understood...

You are obviously quite knowledeable about this. As I try to be a better car guy and learn to take better care of my vehicles, I should probably add 'proper tire care' to the list of things to do right. I do buy what I feel are good tires, but I don't do things like personally inspect/track tread wear or take care to do proper measurements like you describe...

I have used the less reliable science of 'trial and error'... My tires on my cars are rated for max 44 and 51 psi. I have found that 34-36 psi gets the best mileage for both. I don't know if that really equates to best care and longest tread life, but my tires have tended to last a bit past the rated mileage, so I've been satisfied...

-----

PS. I've never really considered running my max 51 psi tires at anything close to 45 psi as you do. I admit I've kinda fallen into a pattern of thinking that mid 30s is 'normal' or 'good enough'. You piqued my interest, I'm going to do some more research into this...

[JWSmythe]

I learned from circle track racers. There's an awful lot that goes into it besides buying a chassis, engine, and driving around in a circle.

35psi may be a little high for the tires. As you said, it's good for mileage, but it may be putting a smaller footprint down. I know when Obama went into office, he had suggested that people add a bit of air to their tires to increase mileage. That's exactly why.

You don't want to fill your tires to the listed max, especially when they're cold. They can easily exceed max pressure under harsher conditions (long drives, tire spin, or performance driving), or even if the weather warms up. My tires had lost a notable amount of pressure when it got down close to freezing, so I had to increase the pressure. When it warmed back up, I had to let some air out to bring it back down into their service range.

If I don't know the acceptable tire pressure, I usually fill to 30 to 35 psi. I've run into a few tires that weren't marked on old beaters where the sticker wasn't visible any more. 30 to 35 psi will get you there in one piece.

My ex was leaving for a road trip. She never checks things like tire pressure. She was having problems, so I drove to her to check the car over. The two back tires were low. One was at 10psi (and looked flat). The other was at 20psi, and didn't look so healthy. Since it wasn't my car, and I hadn't had the opportunity to do any preliminary work on the car, I just filled them to 35psi each (per the door sticker), and then went to work on the other problems. Two low tires, heavily overloaded car, and the bastard that took me a while to find was a broken hose clamp on one of the radiator hoses. Of course it was a foreign car (Infinity), so I couldn't see the leak, and it took 15 minutes to move stuff (air intake ducting, etc) to get to the hose clamp.

There's some good info out there on setting up a car based on the tire temperatures, you'll just have to go looking for it. While I was writing that, based on what I already knew, I found a few good resources, but none were complete enough to link in my message.

Just remember, equal temperatures will give you maximum traction and tire life. Higher center temperature will give you better fuel economy, worse traction, and shorter tire life. If it's too high, you'll run the risk of a blowout because of the pressure. It may improve handling but reduce ride quality, as the tire is harder.

Here's a good picture of what I was trying to describe.



Which comes from this setup guide.

Obviously, in a street car, weights change. We burn through fuel (making the rear lighter). We have passengers disturbing the balance. We may have cargo in the trunk or back seats, which also throw the balance off. If you're serious about racing, go with your racing configuration. Day to day, my helmet resides in the trunk, along with some other crap. I'm frequently carrying around other stuff, but come race time, the interior is cleaned out (including floor mats), and I'm back to racing configuration.

I guess I should mention, underinflated tires will have a lower center temperature, and in certain circumstances give you better traction, but it will increase sidewall flex, and especially in low profile tires, will reduce tire life significantly. You'll also feel that the car drives sloppier, since the sidewalls can flex more.



I've seen some good pictures where people were autocross racing, and on hard turns the sidewalls flexed significantly, moving the tread inches away from their normal position. Those pictures are shot by friends generally who catch them in hard turns. Most of them I've seen have been in tall skinny tires. In a tire like on my WS/6 (275-40/17), you shouldn't see it at all unless my tires are underinflated.

In action racing photos with fast exposures can be amazingly useful to find problems that you never knew existed. On my mechanics late model (tube chassis, and sheet metal skin, similar to a NASCAR), we were looking through photos while he was racing, and spotted the fact that the nose drooped at speed (approx 80mph), because one of the supports that held the nose in place had broken. It looked fine in the shop, and none of us had noticed it. He couldn't hear it dragging, because of all the rest of the noise during the race. The marks on the underside of the nose were attributed to loading it on and off the trailer. That in action photo showed that it needed to be fixed. That was a long time ago, when consumer video cameras were very low quality and took VHS tapes, and consumer grade digital cameras simply didn't exist.

There's a whole balance thing that you can work on too, to set your center of balance just right to make the vehicle perform better. The scales cost a fortune, but you can do the same thing with 4 bathroom scales and a bit of leverage (i.e., 2x6's). For optimal performance, it may be worth adding weights in strategic places. My '82 Firebird that I modified, I found was very hose heavy when I put it on their racing scales. I put a heavy weight down in the trunk, which helped move my center of balance to where it belonged. It felt silly having a 50 pound weight in the trunk, but made a world of difference for handling. I haven't weighed out my '00 WS/6, but by the seat of the pants, it feels pretty good. If I weigh it out, it may feel a lot better. Race cars use lead weights mounted to specific points on the chassis. When I did it, it required a full tank of gas (the way I'd show up to the track), with me in the drivers seat, wearing my helmet and racing harness, and anything that wouldn't be in the car for racing removed. Any little bit counts, if you're trying to do it right. If you go to weight it out, you'll obviously need someone else to take the measurements, and/or change the add-on weights.

I should mention, if you were professionally racing, this would all be handled by the pit crew chief. The driver shouldn't have to concern himself with it. His job is to drive. The pit crew chief's job is to make sure the car runs as well as it can. Since I doubt any of us are racing professionally with our street cars, we don't have the luxury of having a crew chief, or even a pit crew. We go out, have fun, and race on tracks as amateurs (usually).

There are a lot of things that we can apply from racing, to driving on the streets, besides apex turns and skid control. The more we apply, the better our vehicles will perform on the streets. Real racers have put years into understanding how to optimize their vehicles best. Take advantage of that, and it may save your life one day. Stupid people do stupid things. If your car is properly tuned (not just the ECM either), you can make your car dance, where it may spin out of control under other circumstances.

[JWSmythe]

I'm trying not to get too far off topic, but here's a page that explains weight and balance for a street car. If you're tuning your car for tire pressure, that's the next thing to look at. They're suggesting to weight it out with a half tank of fuel. A full tank gives you a little extra in the rear. An empty tank (obviously) makes the rear light.

http://www.hotrod.com/howto/113_0309...ion/index.html

[qwk93ta]

Your wheels look good.

[Schmalgar]

More useful stuff

Good stuff, thanks! Now I want my own pit chief...

[TmaxicanA]

i buy the cheap korean made tires with whatever i think will do good...i feel like i am mistreating my tires after reading all that lol

[JWSmythe]

i buy the cheap korean made tires with whatever i think will do good...i feel like i am mistreating my tires after reading all that lol

Don't worry, you are. For the number of people who I know that love their cars, it's pretty rare to find people who really get that far into the tuning. It's kinda silly though, you could spend $30 on a pyrometer and pressure gauge, but they'll drop lots of money into the suspension to fix a handling problem that may just be the wrong tire pressures. It's usually because they found a reference on some board that said "upgrade this.", without knowing why. No offense intended against information online, but you need to know your vehicle, not just take some advice and assume it applied to you.

I got in an argument with with someone recently who was bent on "The pressure the manufacturer says is always right. It's tuned for this vehicle." His pressure was actually low for the tires. It was obvious looking at the sidewalls (per the pretty picture included earlier).

I guess I should also mention, we won't get a lot of sidewall bulge when our pressure is low, since most of us are using low profile tires. Underinflated tires will destroy the sidewalls quickly though.

[TmaxicanA]

Don't worry, you are. For the number of people who I know that love their cars, it's pretty rare to find people who really get that far into the tuning. It's kinda silly though, you could spend $30 on a pyrometer and pressure gauge, but they'll drop lots of money into the suspension to fix a handling problem that may just be the wrong tire pressures. It's usually because they found a reference on some board that said "upgrade this.", without knowing why. No offense intended against information online, but you need to know your vehicle, not just take some advice and assume it applied to you.

I got in an argument with with someone recently who was bent on "The pressure the manufacturer says is always right. It's tuned for this vehicle." His pressure was actually low for the tires. It was obvious looking at the sidewalls (per the pretty picture included earlier).

I guess I should also mention, we won't get a lot of sidewall bulge when our pressure is low, since most of us are using low profile tires. Underinflated tires will destroy the sidewalls quickly though.

i rarely listen to info online, and the factory specs are as you said..a general spec for safety MPG handling ect. not the BEST for that certain vehicle with different tires from factory. in my years of wrenchin' (wich has only been like 4 years lol) i have never seen anyone who knows more about tire pressure than you..your like the world class tire man! ..hats off to you sir(no sarcasm, dont think that.) and i think i will actually get my thermal gun and do this with my bikes tires..as i am much more aware of its pressures than my car.
is it the same procedure checking a bike tire as a car tire?