Larger 195/65-15 Tires And Gps Speed Check...

Ti-Jean

New member
As discussed earlier, I recently had new Yokohama Avid TRZ 195/65-15 tires installed on my CE to replace the stock 185/65-15 Integrity's. I figured that it would be a perfect match on my car since the LE and S already come stock with that larger size and have identical engine and gearing.

A GPS speed check was in order. I thought that Toyota had calibrated CE's speedometers just the same as other models with the bigger tires, so I was expecting a small to negligible positive error, now with tires 2.46% taller.

I did several tests with the cruise control exactly set. Tires are inflated at 31psi front and 29 rear.

All speeds in km/hr:

Speedo/ GPS/ Error %

60-- 60.2-- 0.3%

70-- 70.6-- 0.9%

100- 101-- 1%

110- 111-- 1%

So I was a bit wrong, but not by much as I now have a slight negative error (indicated is slower than actual). When my tires wear out, I should have a negligible error.

And if I remove 2.46% from my GPS indicated speeds, to have a ball park figure for my stock 24.4 in. 185 tires, I would get an indicated 98.5 at an actual 100 and 108.3 at 110.

Also note that the GPS displays no decimal above 100 km/hr.

Any S/LE owners compared their speeds with a GPS?

The TRZ's are great. My CE now drives like the grown up small car that it is.

And with warmer temperatures and Esso XD-3 synthetic 0W-30 in its veins, the engine is barely audible at idle and purrs like a kitten at cruising speeds.


 
Last edited by a moderator:

Larry Roll

New member
One thing to keep in mind is that you are probably not setting your cruise control as accurately as you think -- all you are really doing is holding your indicated speed. I wish they made a control interface for cruise controls which allowed you do dial in the exact speed you wished to maintain, and it would retain that speed in memory so that it could be accurately re-set after a stop or a temporary decelaration.

BTW I didn't know Corolla CE's came with Cruise Control -- or did you have to special order it as an option?

 

GarrettSocling

New member
Why did you decide to go with the TRZ over say, the H4S? Something about wanting a softer ride or better milage, if I understood the post correctly?

How did they turn out? You seem happy, better than stock in every way?


I have a short list of tire upgrades, and the H4S and Harmony's were on the list. Shall I add the TRZ as well?


 
Last edited by a moderator:

Ti-Jean

New member
Why did you decide to go with the TRZ over say, the H4S? Something about wanting a softer ride or better milage, if I understood the post correctly?
How did they turn out? You seem happy, better than stock in every way?


I have a short list of tire upgrades, and the H4S and Harmony's were on the list. Shall I add the TRZ as well?
Yes, mostly looking for better ride/comfort/noise/wet. And they certainly deliver. The stock tires were much noisier over bumps and every one of them was hardly felt compare with the Yokos. As you said, better than the stock tires in every way.

I had the chance to do a static side-by-side comparison between the H4S and TRZ in the same size and surprisingly the H4S's sidewall was no stiffer than the TRZ's. Treadwear is 500 AA-A vs 700 A-B for the TRZ. The H4S would certainly suit the Corolla just fine as it is fairly light car.

The Harmony certainly goes head to head against the TRZ. For crisper handling without the harshness associated with performance tires, I would certainly consider the H4S for a Corolla.

For more agressive drivers, the Bridgestone G009 and BF Goodrich Traction T/A have much harder sidewalls.

It all depends on what you're exactly looking for.

Lary Roll wrote;

"One thing to keep in mind is that you are probably not setting your cruise control as accurately as you think -- all you are really doing is holding your indicated speed. I wish they made a control interface for cruise controls which allowed you do dial in the exact speed you wished to maintain, and it would retain that speed in memory so that it could be accurately re-set after a stop or a temporary decelaration.

 

BTW I didn't know Corolla CE's came with Cruise Control -- or did you have to special order it as an option?"

Although not perfect, I'm fairly confident in the numbers that I reported as the discrepancy I observed was always around 1% faster than indicated. Road was flat and wind was light and I did more than 1 test at each speed and obtained similar results.

My car is a canadian CE with the bigger of the 2 optionnal packages for that model ©. It adds AC, remote power locks, power windows and cruise control. I often noted that cruise is std in many canadian models while optionnal on same US bound models. I think that it is even optionnal on the US LE. Here for 05, the LE comes only in automatic and has fog lights, ABS, alloy wheels, low tire pressure warning and simili wood on the dash. All stuff I can happily make do without.

Hence my improved poor man's LE... All I need to find now is the bigger and padded center console armrest of the LE to swap on mine.

 

euzeka

New member
Although not perfect, I'm fairly confident in the numbers that I reported as the discrepancy I observed was always around 1% faster than indicated. Road was flat and wind was light and I did more than 1 test at each speed and obtained similar results.
Maybe your speedo is simply a bit off too. The analog needle can't be perfect. A better test would be to check the mileage over several minutes and divide by the time. Like, start your timer when the counter turns 10 and stop it when it turns 15. The longer the time interval, the more accurate you can be.

 

Welcome to Corolland

Welcome to Corolland where you can ask questions or find answers on anything related to the Toyota Corolla.

Please join our friendly community by clicking the button below - it only takes a few seconds and is totally free. You'll be able to ask questions about your corolla or chat with the community and help others.
Ask a Question

HTML

Top