I'm looking around and all I find are trailer tires in this size (which brings up a potentially unsafe idea but I'm not going there yet). Anyone know where you can find the stock 185 80 13 tire? Not interested in changing wheel size, thanks.

A recent thread discussing the topic:

https://www.fiero.nl/forum/Forum1/HTML/091638.html

So that other post didn't really have much in it besides nobody else has found 185 80 13 except one dude at a Farm Fleet store (who by the way does not carry that size even by order on their website anymore).

I am going to summarize all the research I did myself today to give a pretty comprehensive list of your options. The 185 80 13 tire size has been discontinued by most tire manufacturers.This is what you can do:

1) Coker - they specialize in low volume specialty vintage tires. You can order tires in the proper size but it will cost you at least $800 for a new set on your Fiero and they will be white walls.

2) Used - You can call used tire stores around your area and see if someone still has some. Used tire dealers are rampant in Detroit metro and I still haven't found a set, only singles. That being said even if you find some they haven't been made for a while so check them for cracks and don't pay much at all. And tires that look good can have shifted belts or be unbalanced and end up being more of a pain than it's worth.

3) Change 13" sizes - Nankang and Kumho make a 185 70 13. You speedo will be 5.9% too fast and your car will be a little more than half an inch lower to the ground. This will doubly not work for me but it is an option. This webpage is a great tool for comparing tires: http://www.miata.net/garage/tirecalc.html

4) Switch to 14" - I was not interested in doing this, I already have 14's but for this project I want the reduced weight and rolling resistance of 13 inch tires. If you are ok with 14's I would say that is your best option as tires and Fiero specific offset wheels are dirt cheap. Check Craigslist and salvage yards, a set of Fiero 14's are $100 max.

5) Trailer tires - There are a host of manufacturers for a 185 80 13 ST or "Special Trailer" tire. Carlises are cheap and have been known to blow apart but if I had to guess I would say the "cheap" tire buyer also doesn't care to check his/her tire pressure as often or had a cheapo installer put them on and they lost pressure and blew from heat. Again that is just my stereotyping but take it for what it's worth. Tire Rack usually doesn't sell junk so I just went there for next options. They have the "Power King Towmax" and the "Goodyear Marathon." Both are made in China and probably suck in every metric compared to a passenger tire with the exception of rolling resistance.

"TRAILER TIRES!!!" You are probably yelling, "This guy is an idiot!" Fair enough, you can stop reading but I'm continuing my somewhat logical but stubborn reasoning behind considering these. I will preface by stating that I am an engineer who works in the auto industry and has lots of contacts. I am consulting with tire engineers and second hand with the major tire manufacturers themselves. I have been through a couple tire classes and have referenced the NHTSA tire guide several times. It is available free here: www.nhtsa.gov/staticfiles/s...cTire_HS-810-561.pdf

Tires are very complex and have been engineered to perform specific tasks. A trailer tire is not designed to deal with torsional loads from drive axles or large side loads as in steering axles. They are designed to support a load and follow a straight path without concern for water evacuation (if the tow vehicle is not hydroplaning then the trailer doing so isn't as big a deal) or ride quality (noise and compliance). Tire grip (coefficient of friction and contact patch) are also not as critical as people typically corner at slower speeds with a trailer than with a car. These details affect which rubber compound is chosen, tread block pattern, belt, sidewall and ply construction, tread depth and the many other aspects of design. For one of my Fiero projects I want to maintain proper tire and engine n/v (rotational speed over vehicle velocity). Reasons for this will be explained later in a build thread. So looking at the two main trailer tire options I like the Marathon better. First and foremost you usually get what you pay for and these are more expensive. It may be better in design and materials which cannot be determined without destructive and expensive testing so I will just assume. The tread patterns are pretty much a wash but I like Goodyear's larger spacing between blocks on the outside for better water flow. They are also a radial tire and Goodyear says they considered trailer "ride" when designing it so maybe I won't shake my fillings out as fast. You can see the two below





Also a note from Goodyear about this tire.

THE GOODYEAR TIRE & RUBBER COMP
ANY, GOODYEAR CANADA INC
PRODUCT SERVICE DEPARTMENT
Page 1 of 2
Product Service Bulletin
Important Information To Better Serve Your Customers
This PSB is Applicable to: U.S. & Canada
May 18, 2011
PSB #2011-13
TO: Goodyear Company Owned Outlets,
Goodyear Contract Dealers,
Goodyear Canada Inc. Dealers
Subject: Tires for Trailer Use Only: Gen
eral Information (
replaces PSB 2006-06)
This bulletin provides important information to help
your customers obtain the best performance from
“Special Trailer” tires. Please re
view the following important points wi
th your trailer tire customers.
Special Trailer (“ST”) Tires
Goodyear Marathon trailer tires are wi
dely used in a variety of towa
ble trailer applications and are
designed and branded as “ST”
(Special Trailer) tires.
•
Industry standards dictate that
tires with the ST designation
are speed rated at 65 MPH (104
km/h) under normal inflation and load conditions.
•
Based on these industry standards,
if tires with the ST
designation are used at speeds between 66
and 75 mph (106 km/h and 121 km/h), it is necessary
to increase the cold inflation pressure by 10
psi (69 kPa) above the recommended pr
essure for the rated maximum load.
o
Increasing the inflation pressure by 10 psi (69 kPa)
does not provide any additional load
carrying capacity.
o
Do not
exceed the maximum pressure for the wheel.
o
If the maximum pressure for the wheel prohibit
s the increase of ai
r pressure, then the
maximum speed must be restric
ted to 65 mph (104 km/h).
o
The cold inflation pressure mu
st not exceed 10 psi (69 kPa)
beyond the inflation specified
for the maximum load of the tire.
General Information
Important trailer tire care information and load / in
flation tables are availabl
e on Goodyear’s Recreational
Vehicle web site at
www.goodyear.com/rv
. Encourage your trailer tire cu
stomers to use this information.
•
Drivers should always obey posted speed limits and reduce speeds when necessary based on vehicle,
road, weather, or traffic conditions.
•
Many trailer manufactures establis
h the recommended tire inflati
on pressure based on the 65 mph
(104 km/h) rated speed for ST tires. In these cases
, the ST tires should be inflated 10 psi (69 kPa)
higher than the trailer placard for speeds up to
75 mph (121 km/h) (wheel must be rated for this
higher inflation pressure).
If the trailer manufacturer’s placard
specifically states that the cold
inflation pressure is suitable for speeds above
65 mph (104 km/h), no additional inflation pressure
adjustment is required.


So if I want to maintain highway speeds of 70 to 75 MPH I will increase pressure accordingly. They issue statements like "for trailer only use" because not everyone thinks about tires like I just have. I know the performance of these are severely limited compared to a 'regular' passenger tire and will be changing my driving style to match. Braking distances need to increase, cornering speeds reduced and pressures closely monitored. I would compare these to driving in bad weather. Most of us take an increased risk when we venture out in rain and snow storms and adjust driving to suit. My biggest concern is accident avoidance with an emergency swerve maneuver. Starting with a decent handling car and fair driving skills I feel 'ok' about this risk. When proposing this idea to the OEM tire engineers they were not immediately dismissing so this may not be my worst idea ever.

I will be straight line highway commuting about 75% of my miles. All tires undergo rigorous testing before a design is approved. I have firsthand witnessed tire torture machines and you would never guess what these pieces of rubber are capable of withstanding. I think buying new tires will have a large enough safety factor to not worry about them doing anything crazy without warning. And if they are terrible then I wasted $362. Not the end of the world. Pending a fair response tomorrow I will most likely buy the Marathons for Fiero use.

I am looking forward to the road-test report..

i don't mean to sound like an a-hole, but there is a reason that they don't make 185/80-13 anymore...that's a crappy tire. I can understand if you have a museum quality Fiero and want an all original look, but I don't understand the fascination with a tire that was crappy even in it's day let alone now when there are many better options available. Even back in the 80s the Fiero came with 14" or 15" wheels for people that wanted better.

No offense taken Jscott. I daily drive a Fiero so I am used to criticism, haha. In fact many people use your argument on the Fiero as a whole. There is a reason they don't make them anymore. Why drive that crappy old car when it was crappy in the day and there are so many better options nowadays. Hell Chevy offered a "better" sports car back in the day. These are for a special project and I will explain why this size is "better" for my build when I write it up.

quote Originally posted by Cheeze_87: These are for a special project and I will explain why this size is "better" for my build when I write it up.

After I wrote that I realized that you must be working on a project that requires the absolute lowest rolling resistance... electric Fiero perhaps? Whatever it is, sounds interesting. I didn't mean to crap on your project. I'm sure it will be cool, but for the average driver they probably won't go to the extremes you mention.

By the way my trailer has 15" wheels, lol.

[This message has been edited by jscott1 (edited 04-22-2013).]

I've ran trailer tires on a motor vehicle actually. I ran 235/85/16 powermax tow kings on a dodge Cummins dually with a stake bed for hauling wood. They never blew out or performed any differently on the truck. They steered well, even with that heavy Cummins! I had one complaint about them though, that being that they didn't ever seem to wear the whole tread face, no matter where the tire pressure was set, they always seemed to ride on the middle portion of the tread. And don't expect much for tread life. My tires were like 1/2 the cost of a normal load range e tire, but I got 25,000 miles outta them. Where a decent highway tread truck tire should have lasted 40,000 at minimum. Would I do it again? No. But if it came down to that being the only tire available for the truck, then yes. I only say no due to the fact that its cheaper for me to buy a real truck tire than a trailer tire that wears out quicker. As far as performance was concerned ... they were like any other tire. And they had pretty much the same tread as the Goodyear marathons had. Basically a knock off of them.

I believe trailer tires are designed to run on the middle of the tread for low rolling resistance and better straight line tracking. All of my trailer tires have a slightly rounded profile.

Cheapo yard wheels.


Begin sandblasting and wire wheeling critical areas to reduce risk of pressure leaks.


Cleaned and degreased, ready for primer.


Aluminum etching primer. Paint later.


Tires are in.


We'll see.

I can almost guarantee that you will not be disappointed, I had great luck with mine on the cummins

Any clues yet about the true nature of this project yet??

This is genius. Can't wait to see you get into the engine management side of things.

quote Originally posted by KurtAKX: This is genius. Can't wait to see you get into the engine management side of things.

Did I miss a post or something? I'm still trying to figure out what he's building.

Didn't miss anything. The Kurt has inside information.

PPG Shop Line Single Stage High Gloss Urethane


Paint in garage, then sun to bake.


Almost done.

Called to get these things mounted and balanced, cheapest place was $75 and they said they might scratch the wheels. I asked how much to balance with lead weights instead of gold and they didn't think it was funny. F- that. I'm a cheap-a** Fiero owner like most of us. I've mounted tires before, I'll do it myself then.

Spray with soapy water and push on the tire inner lip.


Slips right on, saves $8 per tire. Bead seating and balancing $5 per tire.


Tires coming off. 215/60-15 Michelin HydroEdge. Decent. Bought them with 8000 miles mounted and balanced for $200 from a guy that thought they would fit his Impreza. Wheel offset not correct, my win.


Testing phase 1


Initial impression: These suck! Although I'm not surprised based on my rational above. I dropped the car off the jack and started backing out of the garage. I thought I didn't tighten them at first and the wheels were loose because the steering was so light. The reduced scrub radius and smaller contact patch makes it feel like I have power steering! Kind of neat but also gives a sort of numb feeling. Driving down the road I noticed the stick weights from internal only balancing barely rub on the calipers when braking. I've yet to fix this but should get to it this weekend. Ride quality is not nearly as bad as I thought, almost just as good as the Michelins as far as NVH from the road and from the tire itself. Under steady state conditions they aren't bad as long as you are not on grooved concrete. If you are on a grooved surface these will track all over the place. You may get pulled over for drunk driving. Doing a quick lane change or shimmy or Swedish flick like maneuver is downright scary compared to the 15's. The car feels super loose and it feels like the rubber is folder under the car. I checked to see if the rubber was folding under (with the white shoe polish) and they are not. Will be taking some high speed video this weekend to see what is going on. I've put about 100 miles on them so far and starting to get used to the limited capabilities. Will make a detailed report later hopefully with statistics on braking and lateral g deltas. I know nobody cares but hey, I'm dorky and curious.

Now I'm really curious as to what your building to purposely put such sucky tires on... Here's my guesses in no particular order

1) Electric Fiero (been done hundreds of times)
2) Dual engine Fiero (been done once or twice)
3) Duel engine hybrid gas + electric (don't know if this has ever been done)
4) Solar powered Fiero (hmmm)
5) cut holes in the floorboards, Fred Flintstone foot powered Fiero?

quote Originally posted by Cheeze_87: Doing a quick lane change or shimmy or Swedish flick like maneuver is downright scary compared to the 15's. The car feels super loose and it feels like the rubber is folder under the car. I checked to see if the rubber was folding under (with the white shoe polish) and they are not.

The 13's are 80 series, and the 15's are 60 series. Big difference in sidewall flex, not to mention tread width.

------------------
My World of Wheels Winners (Click on links below)

3.4L Supercharged 87 GT and Super Duty 4 Indy #163

It's not a big project and I'm guessing it's been done before, I just don't know to what level of success. I think Kurt has this project confused with my other Fiero project which will be new in the quality in which it is constructed. Don't hold your breath on this one, it's really not even cool, haha! More of a curiosity project.

Also a kid from my college already did a hybrid Fiero, see here:

http://jalopnik.com/5309278...lds-awd-hybrid-fiero

quote Originally posted by Cheeze_87: Short video of tire.

That is some cool video. You get a +1 for the slo mo tire cam. My curiosity is really peaked now. Can you throw me a bone and give me a clue what you have planned??

I think your tire video hypnotized me. Your will is my command...

I wouldnt hesitate using trailer rated tires myself. They usually have at least 2-3 times the plies than car tires. If they ride a little harsh, try playing a little with air pressures. I dont use anything other than stick on weights on any wheels.

[This message has been edited by rogergarrison (edited 05-13-2013).]

quote Originally posted by rogergarrison: I wouldnt hesitate using trailer rated tires myself. They usually have at least 2-3 times the plies than car tires. If they ride a little harsh, try playing a little with air pressures. I dont use anything other than stick on weights on any wheels.

I would be concerned with traction, as trailer tires are not designed as drive tires. Probably fine on the rear of a FWD.... maybe.

quote Originally posted by fierosound: The 13's are 80 series, and the 15's are 60 series. Big difference in sidewall flex, not to mention tread width.

My thoughts as well, these are actualy probably living up to their potential.

quote Originally posted by jaskispyder: I would be concerned with traction, as trailer tires are not designed as drive tires. Probably fine on the rear of a FWD.... maybe.

Ok, so Id use them and you wouldnt. Maybe I wouldnt use them for winter snow tires. Theyre DOT approved.