pls91fc

I was wondering if anyone was running 205/55-15 tires on their 7? All the tire sites say they do not recommend changing tire size by more than 3%+/-. This changes the size by 3.29%, I know its not far off but any negative effects by doing this? I can get a great deal on some slightly used tires. Please see attachment for reference. Thanks

RXSpeed16

iTrader: (41)

Your speedo will be off slightly, marginally more wear on the drivetrain and you'll use a little more gas while cruising. On the plus side, slightly better accelleration

j9fd3s

iTrader: (3)

putting 205-50-15's on my gxl was the best thing i did to it! it really woke the thing up, 5th gear was usable too.

Molotovman

iTrader: (49)

You'll be fine. I run 225/50/15 for autocross.

rx7_FREAKKK

iTrader: (1)

I used to have 205-55-15' they wore out and i had 195 60- 15s i put on. Not the same car. Might as well be a caddy. 205-55-15 were goood tires IMO. im going back to those next. Never get 195-60- 15s and any type of 195 tire for the rx7. they are good for traveling on the freeway. But dont try to corner

PvillKnight7

iTrader: (16)

What is wrong with 205/60/15?

MIDNFauciUSN

iTrader: (8)

Too much real estate! They wear out my Armor-all can too quickly

rx7_FREAKKK

iTrader: (1)

Too much sidewall is Bad. Trust me, You cant get a feel for the car

pls91fc

I called a few tire places yesterday and I got mixed reviews on changing tire size. If you change the diameter of your tire, in the end you are changing the ratio of the entire drivetrain. Therefore the actual engine RPM will be different and transmission ratios will change. More wear on a 20+ year old car is not a good thing. I have not had any serious problems with my 7 to date (104,000 miles; knock on wood) and wouldn't want to chance it to go 5mph faster on my favorite on ramp . And they dont call the Mazda design team engineers for nothing!

I think I have decided to stick with the stock 205/60VR15 size with some new BFGoodrich G-Force Sports which I have found to be great tires for this car. I have over 50,000 miles on my first set and they are just about to the wear bar. This is pretty good for a summer tire with no tread warranty IMO!

They dont look that bad on the car either!

MIDNFauciUSN

iTrader: (8)

Do they call them that because of the awesome fuel pulsation dampeners they "engineered?"

pls91fc

I think everyone on this forum would agree that Mazda made one amazing car! At least 99% right!

GuiltySoul

iTrader: (7)

then what about 7 owners using 16" rims with 205/55, 225/55, 235/50 etc... i understand that its changing the rotational mass but how much does it really take to destroy your drivetrain? and isn't the bigger you go on rims the more you kill your drivetrain because it takes longer to complete 1 full revolution tuss making the drivetrain work hard by making more than 1 revolution to get the wheels moving?

i can't see using 205/55/15 tires is gonna ruin your drivetrain its a margin smaller, as long as you dont exceed or go way below sidewall size (using truck tires) i cant see a person having problems as soon as the tires are installed

pls91fc

Mass is always an issue when going up sizes in wheels but you still want to keep the diameter of the tire in spec. If you compare the 15" tire and the 16" tire that come stock on the 7 you will see that they have little to no difference in size and weight. You do not want to put a tire on your car that will change the diameter of your tire. There are alot of options for 16" tires that do not change diameter but not so much in 15".

I am not saying that you would see issues arise when you start to drive away from the tire place but 20,000 miles down the road some avoidable issues could show up.

All I know is I like to keep my 7 as reliable as possible and if changing my tire size out of spec may effect the realiability somewhere down the road, I won't be doing it.

PvillKnight7

iTrader: (16)

+1

I don't race my daily driver. The stock tire size is also really common. For about $60 I can find 4 replacement tires in great shape. I mount and balance them myself or pay a local shop $20 if I don't have the time. Once you change the sidewall the tires become harder to find.
225/50/15 is a very uncommon tire size. Many other cars use the 205/60/15 size.

pls91fc

You are right about the 205/60-15 being a popular size but try finding a V rated tire in that size! I believe there may be 3 afforadable options. The way I drive my 7, I do not think a H rated tire would hold up.

RXSpeed16

iTrader: (41)

I agree in theory, but the 'spec' of 3% is a safe number so the big tire places won't get sued. Over 20k, that extra .29% is 58 miles. I don't think I want to drive a car that is 58 miles from catastrophic failure. And overall, tire compound will probably have more effect on drivetrain wear. Anyway, it sounds like you're happy with your choice, so enjoy.

PvillKnight7

iTrader: (16)

Why not?

RXSpeed16

iTrader: (41)

Unless Mass. now has an Autobahn, you won't notice the difference. H-rated tires (130 mph) are just below V-rated (149 mph). Why H is sandwiched between U and V is another mystery.

pls91fc

Knight: Who doesnt like to drive the 7 as it was supposed to be drove! I like to take spirited drives in the mountains once a week.

Speed: Again it comes back to what the manufacturer calls for, V rated not H.

TheAbsence

iTrader: (19)

America's Tire just told me these are discontinued

pls91fc

Did he say that bfgoodrich is discontinuing the gforce sport tire or just the 205/60-15 size of the tire? My local tire shop said he has them in the warehouse avalable.

ColinShark

I'm on my second set of 205/55-15 tires, which I use in the Summer for autocross.

They are great for performance driving. Better gearing,and better response. Probably the worst thing about them is that they don't fill out the wheel wells, which is aesthetic.

In the winter, I run a taller 65 sidewall, which evens out some of the odometer error.

I don't believe the effects on fuel mileage and drivetrain wear are even relevant for an RX-7.

TheAbsence

iTrader: (19)

He said they were discontinuing the tire, but he may be incorrect. I had him search his respective warehouses and he said I was getting the last 2 around in 205/60/15

pls91fc

Shark: "I don't believe the effects on fuel mileage and drivetrain wear are even relevant for an RX-7"

How so? Changing tire size is similar to changing you final drive ratio, no?

Absence: if that is true that sucks. the gforce sports have been great tires for me!

ColinShark

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.