View Full Version : Widebody Wheel Sizing FAQ

05-27-2013, 02:57 PM
st185 wide body wheel faq.

This is a posting that CMS-GT4 has over at AT.net. There are images that go along with it but still have pull those down.

Tune at your own risk.

Update: http://www.tirerack.com now has a st185 on their site when viewing wheels. This is a good reference and source for wheels for the st185.

• Oem st185 alltrac "flower pedal" rim size.
15x6.5 +39 offset or ET
The bolt pattern is 5x100.
The lug thread pitch is 1.5 for aftermarket lug nuts.
Info on converting the bolt pattern to inches for some american wheels.
(Various sized OZ wheels may be found on gtfour models in other countries.)

• The term ET represents offset.
Offset is a very important factor in choosing a wheel size. It will help you determine the clearance between the wheel and the suspension and if the wheel will stick out too far from the fender.
These are good tools for calculating offset of a wheel.

Example and further reading:

Meurz wrote:+45 means a positive offset of 45mm, which would have a smaller lip and the outer edge of the lip sits further inwards compared to a +20 wheel for instance.

For our cars 17x8 +30 would be very nice with a rear 25 mm spacer (effectively changing the offset or ET (short for the German word 'Einpresstiefe' which means 'insertion depth') to +5)

Higher offset = less lip, wheel sits deeper in the arch (mounting surface closer to outside of the wheel)
Lower offset = more lip, wheel sits less deep in the arch (mounting surface closer to inside of the wheel)

•Track width and spacers.
The rear track of the gtfours is shorter than the front which has caused many of us to add rear spacers to add to the looks of the car.
From the owners manual the tracks are listed:
F: 1475mm = 58.1 in.
R: 1440mm = 56.7 in.
A 15mm spacer would be needed on both rear hubs for the front and rear tracks to be equal. The simplest solution is a 20mm DTM spacer that already has studs. Many 15mm spacers and smaller require extended lug nuts to be fitted or there is not enough thread for the wheels to be safely installed. The rear fender has a little more flare than the fronts, so a 25mm spacer is more common which causes the rear track to be wider than the front. Due to the cost of and simplicity 4 identical sized wheels are run on all 4 corners of the st185. It make rotating tires much easier. Especially since the fronts wear much faster than the rears.
A lower offset wheel for the rear would be a better solution but due to the limited availability of low offset wheels in 5x100 bolt pattern, it is usually a costly option. Having different wheel offsets in the front vs the rear will prevent you from rotating them.
If you choose to go the custom route for rear wheels, you can use the track data along with the offset data to help you pick your custom sizes.

Staggered ET example: If I have a 17x9 30et wheel on the front of the car and I wanted a custom rear wheel. I would subtract the size of the spacer I would use from the offset's number to get my custom rear et. If I would use a 20mm rear spacer, then I would need a 10et rear wheel for the outside of the rim to sit in the same place as the 30et wheel with a 20mm spacer.

Note: spacers can be used on the front as well, but you may require longer studs depending on the spacer design and size.

Use this tool to compare new wheel offsets to the oem offset and determine proper fitment.
Offset calculator: http://www.1010tires.com/WheelOffsetCalculator.asp
A good comparison is using the stock width and offset (6.5 +39) as the minimum tolerance and a 9" width with +30et as maximum. If the wheels specs you are considering fall within these specs, you wheels will most likely fit.
Note: 17x9 30et wheels have been tested with proper fitment on alltracs with 25mm rear spacers. It may be possible to go slightly larger, but there is no verified data that there will be no rubbing. (see fender rolling)

• Extended wheel lugs:
These are a longer version of the wheel lugs. They are required for some aftermarket wheels, or if you are using a wheel spacer that does not have built in studs.

• Face design.
The stock alltrac brakes are not that larger or bulky, so most wheel's face designs will not be as much an issue. If you have larger or aftermarket brakes, you may need to go to the brake manufactures website and download a brake clearance gauge. It is a cut out piece of paper that will help you determine if the wheels you are considering will clear your brakes.

•Tire size:
Stock tire size is: 215/50/15
Here is a quick break down of the numbers.
215 = the tire width.
50 = Aspect ratio. This number is the % of the tire width. So the 50 means 50% of 215. A 50 profile of a 275 width tire will be taller than a 50 profile of a 205 tire because it is a percentage of the width section.
15 = wheel diameter. This number has to match the diameter of the wheels you use.
For further reading check out this link.
http://www.1010tires.com/tech.asp?type= ... ral#sizing

This is a very popular tool for helping you choose tire size.
Most people want the same rolling diameter for their new tires as the oem. This will allow the speedo to read correctly. The rolling diameter of all 4 tires must be identical or very close to prevent damage to the center diff on the alltrac. More information on this damage can be found in these forums.
Tire width vs wheel width information can be found on the tire manufactures website or in this link.
http://www.1010tires.com/tech.asp?type= ... ral#sizing

Note: Some alltracs have made full race setups and run 275/40/17 sized race tires (which are larger in size than the standard street tire) with some modification under the fenders.
255/40/17, 255/45/17 Street tires have also be made to fit by only rolling the rear fenders. Larger tires for performance driving can be fitted but can change your rolling diameter. Make sure you do plenty of research when choosing a tire size for your car for safety and proper fitment.

• Fender rolling.
Rolling the rear fenders is often required when running a wider wheel with a low offset or spacer. It all depends on tire size and how much travel you have in your suspension. There is plenty of info on rolling fenders online. You can either have it done professionally, rent the tool yourself, or you can use a heat gun and baseball bat. Search the forums for more information.

• Compatible bolt pattern. Since 5x100 wheels are often difficult to find for the alltrac, here is a list of other cars that share the same 5x100 bolt pattern. This list may help you locate more wheel options.

Audi TT (99-up)
Buick Century (80-89)
Buick Skylark (81-97)
Buick Skyhawk (81-89)
Cadillac Cimmaron (81-88)
Chevrolet Beretta (87-up)
Chevrolet Cavalier (all)
Chevrolet Celebrity (80-89)
Chevrolet Citation (80-86)
Chevrolet Corisca (87-up)
Dodge Aries (86-89)
Dodge Daytona (85-93)
Dodge Dynasty (88-93)
Dodge Lancer (85-89)
Dodge Neon (97-up)
Dodge Neon (94-96 5 lug models)
Dodge Shadow (87-94)
Dodge Spirit (89-95)
Dodge Stratus Sedan (95-up)
Lexus ES 250 (90-91)
Oldsmobile Achieva (92-up)
Oldsmobile Ciera/Cutlass/Calias, non HD/cruiser model (82-91)
Oldsmobile Firenza (82-88)
Oldsmobile Omega (80-85)
Plymouth Acclaim (89-95)
Plymouth Breeze (96-up)
Plymouth Caravelle (85-89)
Plymouth Neon (96-up)
Plymouth Reliant (86-89)
Plymouth Sundance (84-94)
Plymouth Voyager (86-96)
Pontiac Fiero (84-88)
Pontiac Grand Am (85-98)
Pontiac Grand Prix (99-up)
Pontiac J-2000 (82-84)
Pontiac Phoenix, if came w/ factory 14s (83-84)
Pontiac Sunbird (85-94)
Pontiac Sunfire (95-up)
Pontiac 6000, some cars (82-89)
Pontiac Vibe (03-up)
Toyota Camry (83-91)
Toyota Celica (86-up)
Toyota Matrix (03-up)
Subaru Impreza, WRX (non-STi) (93-up)
Subaru Impreza WRX STi (04)
Subaru Legacy (95-up)
Volkswagen New Beetle (98-up)
Volkswagen Corrado V6 (93-94)
Volkswagen Golf V6 (93-98)
Volkswagen Golf (99-up)
Volkswagen Jetta V6 (93-98)
Volkswagen Jetta (99-up)
Volkswagen Passat V6 (92-97)

• Custom made wheels:
Some wheels can be custom ordered or made to your specs. After doing all the proper research and being willing to spend larger amounts of cash you can purchase wheels exactly the size you require. Here is a short list of some of the manufactures who make custom wheels. Expect to pay 500-1000 per wheel. (Prices not for the faint of heart.)
http://www.vividracing.com/catalog/ame- ... 36451.html
http://www.vividracing.com/catalog/work ... 11246.html
http://www.vividracing.com/catalog/fiks ... 34409.html

Others have been listed in the master wheel spec thread, so spend some time browsing other styles and specs or even share your own.

• So what will fit my car?
If you managed to read all this, and still have no clue I have compiled a list of photos with various specs for wheels and tires that have commonly fit the st185 widebody.

Stock 15x6.5 39et (No Spacer)

15x7 35et

16x7 30et

17x7 40et (25mm rear spacer)
205/40/17 (Same rolling diameter as stock)


17x7.5 33et

16x8 38et

17x8 35et

17x8 30et

17x8 35et

17x8 48et 15mm spacer: front, 25mm spacer: rear.

18x8.5 35et.
25mm spacer: rear
Stock Suspension

17x9 38et
25mm spacer: rear
Tein HA coilovers

17x9 30et
Stock suspension

17x9 25et (front), 3et (rear)

I did leave a few of the odder setups out to avoid confusion.

06-04-2013, 11:27 PM
Great thread Mike. Clear and simple read too. Once you get the photos in and are done, please let me know and we can add it as a sticky for quick reference. :)

06-05-2013, 03:37 PM
One thing these are missing is camber specs. More negative camber will, typically, allow for more tire clearance.

I used to run a 245/35R17 on a 17x9 et+30 with a 25mm spacer in the rear.
2.7* of negative camber in the front, 2.0* camber in the rear and roll fenders.

06-05-2013, 06:48 PM
One thing these are missing is camber specs. More negative camber will, typically, allow for more tire clearance.

I used to run a 245/35R17 on a 17x9 et+30 with a 25mm spacer in the rear.
2.7* of negative camber in the front, 2.0* camber in the rear and roll fenders.

Good call Joey. If possible, perhaps you could link in or add some info about camber relation. (just a general thing if you have time)