Anyone running 205/55-15 tires?
01-06-12, 01:00 PM
#26
Full Member
Thread Starter
Shark: I wasn't so much disagreeing with the fuel efficiency portion of your satement as we all know the RX7 is a sports car. I am more concerned about the effects on drivetrain wear, etc.
01-06-12, 02:21 PM
#27
Today's math fun fact. The S5 NA's and S5 GTUs rear ends had 4.1 and 4.3 ratios respectively. That's a 5% difference, but they were equipped with the same wheel/tire combo. All I'm saying is that 3% difference is a made up number and there are options that work.
01-06-12, 08:25 PM
#28
... is there really a discussion on the pros and cons of tire size for stock wheels?
The damage being done by changing series of tire has to be so minimal it would almost be non existent. These cars are already 26-20 years old, if it breaks fix it. A bigger set of wheels may do damage with the added weight and larger tire diameter but changing the series your running by +/- 5 or 10... idk, I would run it. But Im also running 18x8s.
The damage being done by changing series of tire has to be so minimal it would almost be non existent. These cars are already 26-20 years old, if it breaks fix it. A bigger set of wheels may do damage with the added weight and larger tire diameter but changing the series your running by +/- 5 or 10... idk, I would run it. But Im also running 18x8s.
01-06-12, 10:20 PM
#29
... is there really a discussion on the pros and cons of tire size for stock wheels?
The damage being done by changing series of tire has to be so minimal it would almost be non existent. These cars are already 26-20 years old, if it breaks fix it. A bigger set of wheels may do damage with the added weight and larger tire diameter but changing the series your running by +/- 5 or 10... idk, I would run it. But Im also running 18x8s.
The damage being done by changing series of tire has to be so minimal it would almost be non existent. These cars are already 26-20 years old, if it breaks fix it. A bigger set of wheels may do damage with the added weight and larger tire diameter but changing the series your running by +/- 5 or 10... idk, I would run it. But Im also running 18x8s.
The challenge has been set, GO!
01-07-12, 08:14 AM
#31
Ban Peak
iTrader: (49)
As stated before, running a smaller tire gets you more tire rpm. It's also slightly lighter than a stock tire, which puts less stress on your suspension and brakes.
In my opinion, it's less stressful for the far. It will make you accelerate a very tiny bit faster, and you will have a lower top speed.
Have any of you ever seen vehicles that spec for..... MULTIPLE TIRE SIZES? They are very common........
This whole argument is dumb. There is a minimal difference, the only thing you'll notice is your speedo being SLIGHTLY incorrect.
01-07-12, 10:03 PM
#32
kumho ecsta ast H rated 400a/a treadwear 225/50/15, around $70 bucks a tire. Best $300 bucks i spent besides my coilovers lol.
my speedo is off by about 2-3mph @ 60mph, fuel mileage really didn't change much, less stress on the clutch (lighter flywheel) due to ratio differences, and acceleration improved greatly. That extra wear BS is all fooey lol
**** bridgestone, and BFG's..... had horrible luck with both of them in 215/60/15 sizes.
my speedo is off by about 2-3mph @ 60mph, fuel mileage really didn't change much, less stress on the clutch (lighter flywheel) due to ratio differences, and acceleration improved greatly. That extra wear BS is all fooey lol
**** bridgestone, and BFG's..... had horrible luck with both of them in 215/60/15 sizes.
Last edited by lim_fc3c; 01-07-12 at 10:06 PM.
01-08-12, 01:47 AM
#33
I have gone up and down in both tire and wheels sizes many times. Two years ago i was autocrossing with 235/40/17s. I didn't have as much acceleration, but it cornered great.
But going to a smaller tire is different. Plus, the change isn't much. It certainly isn't enough to cause additional wear. A 205/60/15 is 24.7", while a 205/50/15 is only 23.1". so it would effectively lower your overall gear ratio. Giving you some added torque for launches and accelerating. This is exactly what I'm going to do after I get my car ready for next seasons races.
the smaller tires will, however, require higher RPMs at highway speeds. It's a 6.5% difference. So with your car reading 60, you would really be going something like 56. It's probably possible to change the speedo gear to make it accurate.
If you want to talk about drive train wear with tire size, then come and play with my 4x4. 33" tires replace 27" tires, 10% larger difference and something like 35 pounds heavier. Front wheel bearing are serviced often on that truck.
But going to a smaller tire is different. Plus, the change isn't much. It certainly isn't enough to cause additional wear. A 205/60/15 is 24.7", while a 205/50/15 is only 23.1". so it would effectively lower your overall gear ratio. Giving you some added torque for launches and accelerating. This is exactly what I'm going to do after I get my car ready for next seasons races.
the smaller tires will, however, require higher RPMs at highway speeds. It's a 6.5% difference. So with your car reading 60, you would really be going something like 56. It's probably possible to change the speedo gear to make it accurate.
If you want to talk about drive train wear with tire size, then come and play with my 4x4. 33" tires replace 27" tires, 10% larger difference and something like 35 pounds heavier. Front wheel bearing are serviced often on that truck.
01-08-12, 12:03 PM
#34
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Yeah, it is changing the final drive ratio. I guess you would call it the final final drive ratio.
An RX-7 is not an economy car, it's a sports car. Resources you expend making your RX-7 fuel efficient should either:
A: Be spent on a naturally fuel efficient car or...
B: Be spent maximizing the RX-7s other fun traits, which don't include fuel economy.
The stock tire size is a product of 80s tires, and expectations for comfort and looks from the time period. Modern cars run shorter sidewalls. An RX-7 is at home on the shorter sidewalls. The shorter gearing is a benefit. The gearing will still be taller than the stock gearing of a TurboII. An NA has less power to play with. Like jdfd3s said, it wakes up the car.
If you have a lower mileage 7 that's showroom stock, the 60 series has the benefit of keeping the factory look and feel.
If you asked one of the original Mazda engineers this question today, they would recommend the 55 series for performance driving.
An RX-7 is not an economy car, it's a sports car. Resources you expend making your RX-7 fuel efficient should either:
A: Be spent on a naturally fuel efficient car or...
B: Be spent maximizing the RX-7s other fun traits, which don't include fuel economy.
The stock tire size is a product of 80s tires, and expectations for comfort and looks from the time period. Modern cars run shorter sidewalls. An RX-7 is at home on the shorter sidewalls. The shorter gearing is a benefit. The gearing will still be taller than the stock gearing of a TurboII. An NA has less power to play with. Like jdfd3s said, it wakes up the car.
If you have a lower mileage 7 that's showroom stock, the 60 series has the benefit of keeping the factory look and feel.
If you asked one of the original Mazda engineers this question today, they would recommend the 55 series for performance driving.
mazda's tire sizing is actually fairly logical, they run fairly consistent sizing. although the side wall depends on the wheel diameter, so a T2 is a 205/50/16 and the NA is 205/60/15, the overall diameters are really close. the Rx8 is 225/45/18 or 225/40/19, again really close.
i did do the math 205/50/15 vs 205/60/15 is like going from 4.10 to 4.4 in the diff, and its much much cheaper!
