1992rs/ss

This seems like a history question so posting here. My 92 RS came from the factory with the Z28 wheels. As a result I always thought I had the 245/50R16 tires until I went and looked the other day and see 235/55R16 is what is actually on it. Tirerack confirms this as a factory size possibility. Now with these two tires you have a difference in height of over 1/2". This would put the speedo off from one car to the next by a little over 2%.

My questions would be, were the transmissions fitted with different speedo gears depending on the factory tire size? Did I get the 235 because it is an RS and not a Z? Did they calibrate the RS gauge cluster to account for this height difference? I had the upgraded RS suspension as well so I am not sure why 235/55R16 would have ever been on my car

Slater126

iTrader: (1)

A 235/55R16 tire is 26.1" in diameter and goes 797 revolutions per mile (BF Goodrich Traction T/A). A 245/50R16 tire is 25.7" in diameter and goes 810 revolutions per mile (BF Goodrich G-Force Sport). So yes, they would have different speedometer gears to account for that difference.

I have no idea what an "upgraded RS suspension" is but RS models in 1992 came with one of two tire sizes -- P215/65R15 or the ones you have when the 16" wheel option was ordered. Your tire size was also standard on Z28s except convertibles. Z28s with the G92 package and Z28 'verts got the P245/50ZR16 Goodyear GSCs. The P245 tires were not available on the RS.

1992rs/ss

The upgraded RS suspension was something like FE41 code or something like that.


Does anyone know what the two speedo gear part #'s were? I am actually putting new rims and tires on and 275/35R18 is within .2% to the 245/50R16 height

navy02ws6

According to the Camaro White Book, F41 was not available after 1985. Also it does not list any suspension options for a 92 RS. Slater126 looks to be correct. All RS's that were ordered with factory 16's came with 235/55/16's; apparently you couldn't get 16s in a V6 RS.

Interesting since I thought most 92 RS's were V6's with 16's. Guess I was way off. I actually also thought that 16s were standard on all Camaros from 1991-02. Oh well. Now I know that 15s on an RS always means V6!

Slater126

iTrader: (1)

Interesting, good catch. The White Book definitely says the P235-16 tires required the LO3 (V-8) in the 1992 section but it doesn't say vice versa, which implies you could get a V-8 RS with 15s and 15s wouldn't always mean V-6. Oddly, the 1991 section of the White Book is silent on this, as is the 1991 brochure. So does that mean you could get 16s on a V-6 Camaro in 1991 but not 1992?

Can anyone clarify this issue? Need to keep the 1991-92 tire saga straight. You practically need a flow chart, LOL!

1992rs/ss

Hmmmmm, I have my build sheet at home, will have to take a look at it again.

Question still remains, how did they account for the taller tires on the z28 rims? Almost would make more sense that the speedo gauge itself would have been were the adjustment was. Seems like a pain if it was different gears in the trans. If anything for the fact it would be impossible to tell the RS 700R4 from the Z version on the outside

1992rs/ss

quick calc on height the 15" with the tires mentioned above would be 26" and the 235 on a 16" would be 26.17" or just over 1/2 a % larger so probably no significant reading difference in speed with either. this further would make me believe the adjustment was in the calibration of the RS gauge. cluster.....thoughts?

paul_huryk

yes, the RS with the 16" wheels did come with the 235-55-16 tires, even harder to find today than the 245-50-16 ones...

Slater126

iTrader: (1)

Yup, it's an oddball tire size. Tire Rack has three versions, but none of them are high performance. There's 20 versions of the 215-15 and 11 versions of the P245-16.

okfoz

1992
1) the 245-50R16 Tires were ONLY available with the FE2 (Handling)
2) The 235-55R16 Tires Came with the F41 (Firm Ride)
3) The 215-65R15 Tires Came with the FE1 (Soft Ride)

John

Slater126

iTrader: (1)

To clarify, that''s for Firebirds. No performance suspension options appear on the option sheet for Camaros. You got the P245-16 tires with G92 and 'Vert Z28s, P235-16s with regular Z28s and RS models with 16" rims, and the P215-15s with regular RS models.

1992rs/ss

I knew I wasn't crazy. here is a shot right from my build sheet which was inside the center console. F41......



Also here is the coding for wheels and tires

okfoz

Actually, that was for Camaros f...

CAMAROS, 1991 & 1992
1) the 245-50R16 Tires were ONLY available with the FE2 (Handling)
2) The 235-55R16 Tires Came with the F41 (Firm Ride)
3) The 215-65R15 Tires Came with the FE1 (Soft Ride)

NOTE: Not ALL of the Z28 Convertibles got the 245-50R16 Tires. (About 95 + in 1992 and 2134 + in 1991 Got FE2 with the 245 Tires)


FIREBIRD, 1991 & 1992
1) the 245-50R16 Tires were ONLY available with the FE2 (Handling) GTA & Formula, & Optional on Trans Am.
2) The 215-65R16 Tires Came with the F41 (Firm Ride) Trans Am Only
3) The 215-65R15 Tires Came with the FE1 (Soft Ride) Firebird only

Ashton89iroc

thank god i found this thread! haha. I'm in a bit of a pickle and need some help, my situation is this...

I drive an '89 IROC-Z, I have the 16" iroc rims off an '87 IROC with 235/55 tires on them, and a rebuilt 700r4 transmission out of a '91 Z28. (long story short, my '89 was stolen from me, wrecked and i am in the middle of rebuilding it) so my problem is that my speedometer reads around 5 miles off....says I'm going 55 MPH when im actually going 60 MPH.

now, what speedometer gears do i need to put in the trans to make the speedometer read accurately? I still have the original transmission from my '89 (its stuck in first gear, need to do some valve body work) would using the gears from the original transmission fix my problem?

okfoz

From the description, it sounds like part of your problem is the fact that 235/55-R16 tires are larger diameter than 245/50R16 tires. The Revolutions per mile are 786 for the 245/50 Tire vs 770 Revs for the 235/50 Tire.

There are other factors to consider, such as what is the rear axle ratio on your car. Also considering that a 1991 transmission would have the electronic speedometer, whereas I thought that the 89 was the last year for the cable driven speedometer in the Camaro.

John

Ashton89iroc

when I bought it I was told it was from a '90 or '91 Z28, but it does have the speedometer cable connection, otherwise i'm sure it wouldn't be compatible, so maybe they had the year wrong. in any case, I have the stock 9 bolt, 2:73 rear end. To be perfectly honest, the math behind finding the proper speedometer gears is a bit over my head and I don't have the money to keep buying different ones to see if they work or not.

If at all possible, i'd like a straight "This is the gear you need" answer.
If you could do that for me, it would be MUCH appreciated since I've been doing research on this problem for a month now and haven't found a straight answer. Every answer i find is for people swapping from 2:73's to 3:23's or something else, seems to me like nobody is running 235/55 tires and nobody likes the stock 2:73's. If you guys could get past my inability to do somewhat complex math, i'd greatly appreciate it! hahaha.

my specs are: 235/55r16 tires, 700r4 transmission, 9 bolt 2:73 rear gears. I do not know what speedo gears are currently in the transmission and I don't currently have the luxury of taking it apart to check.

TTOP350

iTrader: (8)

John, whats the word on 92 Trans am verts with 16" wheels and non WS6? My friends car had the 235/55? 16s on it when he bought it. I'm fairly sure They were org tires. I'm getting the door sticker info as I type this.

okfoz

It might not be a straight as you want answer

There in-lies another problem, the Borg & Warner was 2.77 not 2.73...

I need a few questions answered.
1) What engine do you have, LB9 or L98, those would be the only two with the 9 Bolt B&W
2) Do you have G92 or not?
3) At 70Mph what does your Tach read? (that would answer question 2)

As a rule of thumb, A...
2.73/2.77 gear @ 70 Mph is Tach reads: 1750 RPM
3.23/3.27 gear @ 70 mph is Tach reads: 2000 Rpm
3.73/3.70 gear @ 70 mph is Tach reads: 2250 RPM
or there about.

Tony,
As per the 1990, 1991 & 1992 dealer brochures:

Level I: P215/65R15
Level II: P215/60R16
Level III P245/50R16 (WS6)

Ashton89iroc

I just ran outside to check my RPO codes. I have GH3, G80, and L98. hope that simplifies the problem.

okfoz

Every now and then I am made to eat crow...

I just learned that the Firebird had the following

Level I: P215/65R15 (FE1)
Level II: P215/60R16 (F41)
Level III P245/50R16 (WS6 FE2)

And the Camaro had the following:
Level I: P215/65R15 (FE1)
Level II: P235/55R16 (F41)
Level III P245/50R16 (FE2)

JT

iTrader: (1)

Do you have the VIN? I'd like to check it.

TTOP350

iTrader: (8)

My bad, his car does have 215/60/16 listed on the door sticker.