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My car is currently fitted with 165 x 80 x 13 would this be stock? I have tried searching but cant find what they would have left the factory with. I now need 2 new rears and can only find 165 x 70 x 13 locally. Any help appreciated.
 

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My car is currently fitted with 165 x 80 x 13 would this be stock? I have tried searching but cant find what they would have left the factory with. I now need 2 new rears and can only find 165 x 70 x 13 locally. Any help appreciated.
The original European GT tire size was a 165HR13. I'm not sure what aspect ratio that *really* is, but I always assumed it was 165/80-13. Others say it is closer to 165/78-13.
 
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Another nice option as far as keeping things stock looking and also remains close to the original specs are 175 70R13.
 

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Thanks I cant believe it is so hard to find what the actual ratio was. That said I need to replace all 4 tires and would like to keep it as stock as possible but also practical as I cant fine the 80 x 13s. Will go with 175, I presume they fit ok an don't hit the arches .

cheers

Rob
 

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Opeler
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My car is currently fitted with 165 x 80 x 13 would this be stock? I have tried searching but cant find what they would have left the factory with. I now need 2 new rears and can only find 165 x 70 x 13 locally. Any help appreciated.
The stock 165x80-13 has a calculated diameter of ~23.4 inches (594 mm) and the 165,70-13 tire has a diameter of 22.1 inches (561mm).

This means that when the stock tire size is going 60mph, the 165x70-13 tire is only going 56.7 mph at the same RPM, resulting in a speedometer error of about 5.5%.

If you could find 185x70-13 tires, then you would only have a negligible .5 mph error at 60 mph.
 

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Thanks I cant believe it is so hard to find what the actual ratio was. That said I need to replace all 4 tires and would like to keep it as stock as possible but also practical as I cant fine the 80 x 13s. Will go with 175, I presume they fit ok an don't hit the arches .

cheers

Rob
No there is no clearance issue or rubbing with that size and are much more commun. I bought the ones in the picture brand new on sale @ 170$ for all four! That was about five years ago tho.
 

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No there is no clearance issue or rubbing with that size and are much more commun. I bought the ones in the picture brand new on sale @ 170$ for all four! That was about five years ago tho.
If you have a source for those Radial TAs, please share it. I haven't been able to find those at all.
 

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Stock tire size is 165/80x13 you can replace that size with 185/70x13 this will keep the same reading on the speedometer if you use an other tire size the speedometer will show a higher or lower speed than you are actually driving
 

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Your Noble Friend ;-)
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"Later" European 1.9 GTs (1972+) came optional with 185/70/13 tires from the factory, which every GT person there would consider "stock size" as well, besides the 165/13 (= 165/80/13).
The GT 1.1 actually came on 155/(80)/13.

Dieter
 

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13 inch tires are getting hard to find here in the States. I previously had Yokohama A008 in 205/60-13 on the rear and 185/60-13 on front. I loved the look of those but I could only find those sizes in a cheap tire these days. I ended up going with Michelin 175/70-13 on all four wheels. Rides very nicely but doesn't look nearly as good with my aftermarket wheels.
 

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instead of the 165/80x13 or the 185/70x13 you could use a 155/80x14 or a 175/70x14 and even a 195/60x14
 

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Befuddled
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If you go with the 175/70-13
Tire Rack has several in the $40-60 range.

just search as a 90 Honda CRX to make it easy
 

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The stock 165x80-13 has a calculated diameter of ~23.4 inches (594 mm) and the 165,70-13 tire has a diameter of 22.1 inches (561mm).

This means that when the stock tire size is going 60mph, the 165x70-13 tire is only going 56.7 mph at the same RPM, resulting in a speedometer error of about 5.5%.

If you could find 185x70-13 tires, then you would only have a negligible .5 mph error at 60 mph.
Just bought a GT that had the original never used spare in the car. 165 R 13. It's measured diameter is 22.9". A 175 70 13 measures 22.7" and a 185 70 13 measures 23.1. Both of these tires are suitable replacements and represent more rubber on the road. Unfortunately, most 45 year old speedometers are way off on the calibration. My GT with 185 70 13's reads 80 on the speedometer at an actual 75 MPH. I've been wanting to tear an old speedometer down and see how it can be calibrated. I know that VDO will do this at a significant cost.
 

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Just bought a GT that had the original never used spare in the car. 165 R 13. It's measured diameter is 22.9". A 175 70 13 measures 22.7" and a 185 70 13 measures 23.1. Both of these tires are suitable replacements and represent more rubber on the road. Unfortunately, most 45 year old speedometers are way off on the calibration. My GT with 185 70 13's reads 80 on the speedometer at an actual 75 MPH. I've been wanting to tear an old speedometer down and see how it can be calibrated. I know that VDO will do this at a significant cost.
Differences overall are minor.. and sure differences in tire structure, and wear can affect the overall diameter within that range as well.

Im starting to trust my GPS speedometer more than the one on the Kadett.
 

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Differences overall are minor.. and sure differences in tire structure, and wear can affect the overall diameter within that range as well.

Im starting to trust my GPS speedometer more than the one on the Kadett.
Tell us about your GPS speedometer. Is it an App, part of a GPS unit for plotting a trip, or do you have something permanently installed? Does it respond quick enough to be useful for general use, or is it only useful when holding a steady speed for a while?
 

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Tell us about your GPS speedometer. Is it an App, part of a GPS unit for plotting a trip, or do you have something permanently installed? Does it respond quick enough to be useful for general use, or is it only useful when holding a steady speed for a while?
All 3 are apps for my Windows Phone :

I have one that uses the OBD2 plug

Then there is the standard GPS map app (Nokia Drive), it works well

Then there is an App I use that uses GPS and creates a "speedometer" on my phone that I actually use as my speedometer. I have even made a mount for it for my dash.

All work fine, in slow or highway driving.
 

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GPS as Speedometer

I have an ancient Garmin GPS unit. If you have the map loaded but aren't in directions mode, the speed shows in the bottom right. If you click on that bottom right field in any mode, it switches to a "dashboard" mode and shows a speedometer and a bunch of other info, see attachments. I used this when I had the wrong speedometer in the car. When I put in the new speedometer, I checked it against the GPS and seems very close. I running a new set of 185 70R13 tires on the original rims.
 

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