meangreen92

iTrader: (1)

the 16x8 GTA wheels, which mine actually measure 8.5, how wide of a tire can i put for the rear wheels?? the 245's are ok but id like to do at least 255's or better if they fit on the wheel and in the wheelwell...... any ideas???

Zerstörer

You have to measure the inside bead to bead. 255s will throw your speedo off a lil bit.

Forshock 85TA

Correct and Wrong (mostly)

Bead to Bead yes.

Speedo: When you go wider, you make the aspect (height like 45) lower to compensate for the smaller wheel

Example: 245/55-16 = 26.6", 265/50-16 = 26.4" which means 60Mph vs 59.6Mph (analog gauges arent that noticable )

BTW, this isnt a flame just providing a more detailed answer

Zerstörer

Were the stock size 245/50 or 245/55?

Forshock 85TA

Im not sure i have the 15" wheels

But the same methods apply regardless, see:
http://www.miata.net/garage/tirecalc.html

83 Crossfire TA

iTrader: (2)

They are actually 16x8, not 8.5, I just measured a set 2 days ago.

stock tire sizes are 245/50/16, 215/65/15 and 235/60/15 depending on the year, wheel and option packages

meangreen92

iTrader: (1)

wheels origional from a 92 T/A ws6 optioned car.... and from lip to lip just inside that outer flare it measured 8.5...... the car came with 245 50/16 tires..... so going up to 255's or better will screw my speedo???

91blkta

I have also seen 215/60/16 from stock also on some 91 ta's maybe more years but thats the year I have and what the door shows as the stock tire.

meangreen92

iTrader: (1)

mine has the door listing a 245 50/16 tire as factory, but my car is a factory TPI L98 350 car....

91blkta

Your size seems to be more common from factory for a while I thought I had the wrong size on the car till I looked at the door sticker. When you read most posts my size never comes up but I find I can find cheaper tires because they are more of a passenger car tire not quite as wide. Althought there seems to be a lot of touring tires in that size.

Zepher

iTrader: (1)

Don't worry about the speedo when going to a 255/50/16 tire. It's not like it's going to be 10mph off, probably 1-2mph, and you won't even notice it.

I don't notice when swapping from my 275/40/17's to my 255/50/16's on my car.

83 Crossfire TA

iTrader: (2)

Measure it from the widest point that you have the full, inside bead depth and you’ll get 8”, or measure it from lip to lip and you’ll get approximately 1” more then the wheel size on an aluminum wheel (If I remember right those measure 9-1/16” or so). It’s an 8” wheel.

Huh? That’s not listed as a stock size anywhere… what wheels did that come with? FWIW, it would have to be a 16x7 (the widest width wheel that you’re supposed to use a 245/50 on is an 8.5” so the 8” stock wheel would be way too wide for a 215) and I don’t know of any 16x7 f-body wheels. On the 4th gen cars the lower po and early vert versions got 235/55/16’s.

91blkta

I have the black gta wheels with chrome ring which came on the 91' trans am, with the different front to rear offsets. They fit just don't have as big of a footprint as a foot print.

iansane

iTrader: (1)

No. If it's a 91 TA then it didn't come stock with anything but a 16x8" wheel and 245/50r-16 (gsc's I think? who cares...)

The door will list other things besides what might be in your car. It should have the listing for all tires combos from that make/model.

Besides a 60 series tire would be HUGE on a 16" wheel on these cars.

I'd double check.

Zepher

iTrader: (1)

I failed to mention the wheel sizes,
my 17's are 17x9.5
my 16's are 16x9.5

Don 79 TA

her formula 350 ws6 rims measure 8.5 the same way (lip to lip)

but i believe it's still classified as 8

my weld drag lites same thing, claiper on the balancer measure 8.5 but they were 8 when i bought them.

perhaps a 1/4" for each lip???

DuronClocker

iTrader: (1)

As stated above, the car should have 16x8's on it with 245/50R16. I'll have to check the sticker on my '88 to see if it mentions anything about a 215 tire on a 16" wheel.

Also, 215s may fit on an 8" wide rim. For my winter tires, I ran 225/60R16 tires on 4th gen saladshooters (16x8). Those 225s fit without a problem and I didn't see any abnormal wear.

meangreen92

iTrader: (1)

thanks guys, i needed the info cause im due for tires and since the rear wheels dont fit in the front, i wanted to go a little wider... it rains all the damn time down here in FL and traction is an issue to begin with on the t/a...

Zepher

iTrader: (1)

Wider tires are worse in the rain, btw.

meangreen92

iTrader: (1)

interesting...

DuronClocker

iTrader: (1)

Wide tires SUCK in the winter too (ask me how I know). Then again, I don't think you'll see much of that in Florida

Wide tire = more contact area. Same downforce applied (vehicle weight) over larger contact area = lower pressure (lb/in^2). Things are different in dry weather and even moreso with very sticky tires (i.e. slicks).

meangreen92

iTrader: (1)

well when i bought the car someone had put 225 60 16's all around on the car... they were cheap passenger tires and they sucked, esp the rears.. when i stepped back up to the factory size, it handled better and had more traction from 40mph up... anything under 40 no matter what tire i have on theres no traction, just a show.....