Novo

Hi there.
I recently bought 1995 Chevrolet Camaro Z28. It came with stock black painted rims, 235/60 R16 rear and 225/55 R16 front tires. So, I know that in stock Z28 must have 235/55 R16 tires, but in my country it is lack of this size. So I have some questions:
1. What exact rim parapmeters for the stock Z28 rims? I saw 16x8" 5x120.65. But what the ET (offset)?
2. Does the rear and front rims equal for the 4th genereation Camaro?
3. I want to use my car in winter and have 4 spare rims from 4 generation base Firebird (16x7.5" 5x120.65). Whether the normal use of these rims with winter tires? What size of tire? 225/60 R16?
Thank you!

Injuneer

Stock Z28 wheels are 16x8.0" 55mm offset, with a 5x4.75" (120.65mm) bolt circle. All Z28's had alloy wheels, in a pattern called "salad shooters". The steel wheels were only used on the V6 models, and I believe were 16x7.5". I think the Firebird had alloy wheels whether they were V8 or V6.

The same wheel/tire size was used on all four corners of the car.

The "base" tires on a Z28 are 235/55-16 (26.1" diameter). If you car was ordered with the RPO "QLC" Z-rated tire option, the tires are 245/50-16 (25.7" diameter).

The tire diameter affects the speedometer, with the tire diameter needing to be programmed into the computer (PCM). If you change the tire diameter, the PCM will need the new diameter programmed in, or the speedometer and odometer accuracy will be altered.

The tires you currently have in the rear (235/60-16 = 27.1") are a full 1.0" larger than the tires that are supposed to be there, and are causing your speedometer to read 3.4% lower than the actual speed, if you have not had the PCM reprogrammed.

The narrower wheels (7.5" width) are OK for snow/winter tires, which are typically narrower than summer high performance tires. 225/60-15 (26.6") is also an excessive diameter. You would be better using a 215/60-15 (26.1") which was the stock tire size on the V6 models.

Novo

It's a great answer! Thank you very much.

For now I cannot say anything about RPOs for my Camaro, cause at the stickers on the drivers door nothing readable, but when I entering my VIN in GM EPC, it shows that only Z28 option I have. For now I am waiting two cables from China to build my own cable and use GaryDoug's excellent app (Scan9495) to view what it is in the PCM.

I think that my PCM was last programmed in the USA, but tires were on here in Ukraine. So it doesn't matter for now, cause current tires are very poor.

One question more: Is there difference in design between stock V6 and V8 rims? Do I have to check are my rims 7.5" or 8"?

I think that there is no difference in tire I will choose size according to 7.5" or 8" rim width. I don't know...

May I choose 245/50 R16 tires for my stock rims for summer riding?

How do you think, may I will choose the winter tires with excessive diameter cause of the road poor quality in my country?

Injuneer

If you read through GaryDoug's complete Scan9495 thread, he indicates that the quality and features of the Chinese components are constantly changing.

I don't know how the V6 wheels compare to the V8 wheels, other than what I already mentioned. If you check a site like TireRack.com you can look up the specification for various tire sizes. The tire manufacturer determines the minimum and maximum allowable wheel width for each specific tire size.

I'm pretty sure the 245/50-16 tires will work best on the 8" wide wheels.

The taller tire side walls will protect the wheels better from potholes in the road.

Do a search for a website called "compnine". You can enter the VIN (vehicle identification number) and it will give you the vehicle manufacture date, a list of all the RPO codes, and what each code means. Used to be free, but now there is a small charge. Not sure how difficult paying the fee would would be from outside the USA.

GaryDoug

You should be ok with the Chinese cables. But there can be two issues.

1. The wire colors may change from the ones in my instructions. To make sure it is correct, use a multimeter to check the continuity of each wire in the cable being made. On the 16-pin end pin A should go to the ground on the USB end, almost always black. Pin M should go to the RXD and TXD signals on the USB end, usually green and white, but not always. You may have to take the cover off the USB end to make sure. It usually has markings on the circuit board.

2. FTDI has issued a device driver for the chip inside thew USB end of the cable that disables the chip of a non-FTDI-made part (most from China). To be safe, use no driver newer than version 2.8.30. Set your pc to NOT automatically download and install new drivers.

DelSoto

Did the location for RPO codes change after 94? Mine are inside my glovebox. Might check there.

Novo

Yes, I read all of the Scan9495 thread carefully... Two times. Maybe it will be some questions, but only when I get my cables and see it.
When I understood, that 235/55 R16 is very unpoplular tire size in Ukraine (only the tire were in shops year ago was Falken Ziex ZE-502, has a good sporty pattern), started to search this size on US sites including TireRack.com, but most of them show tires with pattern for SUVs or something like this. Nitto has no such size too. Maybe I'm not good in searching, so please point my view, I will be apprecciate...
I forgot to tell, that my Camaro uses wheel spacers, so wider tire will look cool.
Thats why I think to use taller tire in winter.

Yeah, this site tells me that my car was produced january 12th, 1995 with 1995 model year. And for only 5 dollars ready to give 5 complete reports. Will search the way to pay, guess nothing difficult.
In my country such things like electronics are chinese predominantly. So it's Ok.
I read your complete instructions and how-to's already and will try to follow them carefully. You even answered my question before I want to ask, about pins 4 & 5 - how to solder them to one hole.
Already downloaded whole folder with all necessary from your Mediafire place, including right old versions of drivers.
Sad but true - there is a sticker in my glovebox, but it's completely white, all of the legend is missing like it is on drivers door.

Injuneer

The 235/55-16 is getting harder to find. Tire Rack has 3 tires in that size, two Kumnos and a BFGoodrich. They are all "car" tires, not truck or SUV. They are "all season" meaning they are somewhat suitable for winter use, but not in deep snow. The BFG Traction T/AT looks to be the best of what is available.

My search shows there is a Nitto NT450 ultra high performance all season in 235/55-16.

An alternative size, with a diameter close to the 235/55-16 would be a 255/50-16. Again, not a lot of selection, but there is a BFG G-Force Sport Comp-2 that is an ultra high performance summer tire, with a fairly aggressive tread. It will work on a rim from 7.0" to 9.0".

Novo

That's great! I'll try to find these tires in our shops, may be some of them could deliver tires especially for me. Also I'll search the 255/50 R16.
Thank you for your help!

Fatdog2

245-50-16--------------------------245-55-16 for a wider tire I think.---I'm running Cooper ZEON-RS3-A Tires.Run smoothly,Hook up pretty OK.245-50-16
I think they are made in China,but not sure.They use them on Corvettes here in a different size..Hope this helps.

Injuneer

No. Not wider. It would be a larger diameter tire.

If both tires are "245" they both are the same nominal width, about 9.645" wide at the widest point on the sidewalls. "245" is the "section width". To get a wider tire, you would get the 255 instead of the 245. A 255mm / 25.4 = 10.039" wide.

The next number "50" is the "aspect ratio". That is the height of the sidewall divided by the section width, expressed as a percentage. 50 means the sidewall is 50% as tall as the aspect ratio is wide. In this case, a 245/50-16 has a 4.823" sidewall height. The diameter would be 16" + 4.823" + 4.823" = 25.646". A 245/55 (if there is such a size) has a sidewall height of 5.305". That means the diameter of the wheel, plus two sidewalls = 16 + 5.305 + 5.305 = 26.610" diameter.

Note that all tire dimensions are "nominal". There is some tolerance in the actual width of the tire compared to the "245" millimeter dimension, and in the overall tire diameter. It's sort of senseless to express the number in inches to three decimal places, and that was only done to illustrate the principles. The width of the tire is also affected by the width of the rim it is installed on. A narrow rim will squeeze the width narrower, and a wide rim will spread the width wider. The tire manufacturer's data sheet will tell you the acceptable range of rim widths, and the width that was used to measure the tire's section width.

GaryDoug

Ooops, I gave the instructions for a 94 cable, not a 95. I know you have read carefully and know what to do for your 95, but for others that read this topic, substitute pin A for pins 4 and 5 on the 16-pin connector, and substitute pin M for pin 9 on the 16-pin connector.

Fatdog2

God. I must have dropped the ball here.Your right again Injuneer.I ment 255-50-16.It's the wider tire for my rim.Thanks.

Novo

Recently, I found some wheels with 225/60 R16 size for firebird's base 7.5" width rims. It's a new Cooper Weather Master SA2. It were produced in England in 2014. And price is about $62 for wheel. It is only for 0.5" taller and for 10mm narrower than the stock tire size. So it will be only for 0.25" closer to body.

http://www.coopertire.co.uk/img/uplo...2-HV-panel.jpg

What dou you think about this choice? It's for winter riding.

Injuneer

That tire is a "winter touring" type. It is intended for use in ice and snow, with (most likely) a hygroscopic tread compound. While that tread compound grips very well on wet/cold surfaces, it is not very good on dry surfaces. I ran that size tire, with a winter ice/snowtread compound (Blizzak) on my Formula for one winter. Made the car driveable in snow. But once the snow disappeared, the dry traction was poor. Mom & Pop Buick's (what old people drive in the US ) would leave me sitting at the stop light spinning my tires, while they drove off into the distance.

The cold weather compound is typically used only on the outer 50% of the tread, and will wear quickly on dry roads. I have a set of Blizzak WS70's for my wife's Prius (yes.... a Prius) and I wait until the last minute in winter to put them on, and take them off immediately at the first sign of spring.

Check with the manufacturer and see if it is a cold weather tread compound.