Tyre change
- Thread starter janneman
- Start date
There's a nifty tire size calculator on the Miata.net website (see: link). It says the difference in diameter between the two sizes results in a 3.2% speedometer error; that when the speedo says you're going 60, you'll in fact be going 58.1 mph with the /45 ratio tire.
I'd also compare the load index numbers between the two tires just to make sure you don't loose too much capacity; as I recall the load capacity of a tire tends to go down as the sidewall gets smaller (eg, 50 down to 45). There's a good description of what all the numbers mean on Wikipedia (see: link).
This is my first post here; be gentle. My wife has a '07 Mazda 5.
I'd also compare the load index numbers between the two tires just to make sure you don't loose too much capacity; as I recall the load capacity of a tire tends to go down as the sidewall gets smaller (eg, 50 down to 45). There's a good description of what all the numbers mean on Wikipedia (see: link).
This is my first post here; be gentle. My wife has a '07 Mazda 5.
Jannerman, the stock sidewall is short enough already. 45 series tires on the same rims will make for a bumpy ride, not to mentin wheelwells you could rent space in.
Even if these tires were free, I would pass.
BTW< welcome to our nosy, opinionated family.
Even if these tires were free, I would pass.
BTW< welcome to our nosy, opinionated family.
SGT_OKINAWA
Member
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- 2010 Mazda CX-7
CaptainSpalding
Member
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- Mazda 5
First off, welcome to janneman and OldDave. I'm a new 5 owner as well.
There's another great tire size comparison tool here:
http://www.1010tires.com/TireSizeCalculator.asp
Editorial note: I've always been amazed by the current trend toward larger rims and lower profile tires. I understand the purpose of low profile tires, but one can go too far with it on a passenger car. My car came with 17 inch rims, but but I wish it had come with 16's. The roads are generally poorly maintained in my AO and I feel every bump. When it's time for new tires, I'll probably replace the rims with 16's. I like to scoot around town as much as the next guy, but this car will never see a track . . .
The /45 series will lower your car almost 1/2 inch. I would also echo what KBrian said about replacing already-low-profile tires with even lower-profile tires and how that will affect the ride.
There's another great tire size comparison tool here:
http://www.1010tires.com/TireSizeCalculator.asp
Editorial note: I've always been amazed by the current trend toward larger rims and lower profile tires. I understand the purpose of low profile tires, but one can go too far with it on a passenger car. My car came with 17 inch rims, but but I wish it had come with 16's. The roads are generally poorly maintained in my AO and I feel every bump. When it's time for new tires, I'll probably replace the rims with 16's. I like to scoot around town as much as the next guy, but this car will never see a track . . .
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I can't say I'm a new 5 owner -- we've had ours for 2 and 3/4 years (and well over 60,000 miles). I joined (rather than just being an anonymous reader) when I finally saw a question I could answer. :lol:
a lot of perception/acceptability has changed in regards to what people expect. when the '84 corvette came out as the 1st w/ 16" wheels and 50 series rubber, it was groundbreaking. people couldn't believe how short the sidewalls were!
now, 17" are common on people movers, and no one is surprised anymore w/ stuff into the 20's.
I do like how my 5 handles w/ the 205/50's. I don't think its harsh at all. and I was used to 235/65 on my previous car!
CaptainSpalding
Member
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- Mazda 5
In my case it's not a matter of an old codger not being able to accept the new fangled fashion in wheels and tires. It's more an issue of form following function. Whether the barely perceptive benefit to handling is worth the much more noticeable sacrifice in the ride.
BTW, the '84 'Vette's 255/50R16 tires have an inch more sidewall than our 205/50R17's. And the Vette stands a much better chance of seeing a racetrack than a Mazda5, wouldn't you say?
that's not what I was trying to say. what I meant was, short sidewalls are the norm now. the vette was groundbreaking back THEN, but not anymore.
I wasn't saying anything in reference to you or your age.
IMO the ride doesn't suffer in my 5 due to the short sidewalls. my MPV (w/ 225/75 15 tires!) was much harsher over bumps than my 5 so I have no issue w/ the tire choice mazda made.
CaptainSpalding
Member
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- Mazda 5
I didn't think you were trying to offend. Sorry if I gave that impression.
Re: your non-harsh ride - you must live in a place where the roads are better paved.
I guess my comment regarding big wheels and skinny tires isn't an indictment of Mazda USA's tire choice for the 5, but rather an observation that for the last several years many of these design choices have been made with respect to aftermarket sales trends rather than empirical, practical design considerations.
Funktional
Member
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- 2009 Mazda5 Sport MT
Granted I understand the sidewall on a winter tire tends to ride on the stiff side but I installed a set of 195/60-16 Blizzak WS60's on 16" steelies and I miss the supple, more compliant ride of the stock tires. Handling has taken a huge hit but I attribute that more to the winter tread rather than the taller sidewall and slightly narrower tire. I live in Maine. The roads here are terrible winter or summer and I don't see a problem with the stock 17" setup. I truly think it's comfortable and feel that there is plenty of sidewall in the 50 series tires to protect from damage. On that note, I purchased the V because it's a decent people mover, it came with a manual transmission and it truly is a hoot to drive. Since my stock tires had less than 3k miles on them before swapping on the winter setup I'm going to have them replaced with some ultra performance summer tires once April/May rolls around and see if anyone wants to buy the pristine stock tires. I expect a tremendous upgrade in handling and couldn't imagine downgrading to a 16" wheel and tire combo since it would most likely degrade one of the Mazda5's best attributes, it's handling. I think if I were more interested in a comfortable ride while still attaining decent fuel mileage I would have opted for a Dodge Caravan or something along those lines.
CaptainSpalding
Member
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- Mazda 5
IIRC someone said that they also come w/ smaller diameter rotors; the 15" wheels don't fit our cars.
I was actually contemplating using the 17" factory alloys for winter use and getting some 18" summer wheels.
CaptainSpalding
Member
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- Mazda 5
What next?
Funktional
Member
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- 2009 Mazda5 Sport MT
I understand where you're coming from but the data seems to support otherwise. When C&D did their Boss Wagon Mazdaspeed5 writeup they noted that their Mazda5 with forged 18" wheels and tires from an MS3 did .88g's of grip on the skidpad compared to .80 stock and only took 165ft to stop from 70mph. In comparison a stock Mazda5 stops from 70mph in 183ft.
There is absolutely no question in my mind that a Mazda5 shod with stock sized tires will out perform a Mazda5 with the same model tires in a 16" wheel/tire combo. As stated, I think most people purchase a 5 over more mainstream "minivans" because of the zoom zoom factor and I trust Mazda engineers have deemed 50 series tires a necessary part of that handling equation.
I would consider upgrading to an 18" tire/wheel combo for an even better handling advantage however there is a significant difference in price ($40/tire) between a 205/50-17 ultra performance summer tire and a 225/40-18 ultra performance summer tire. In my experience I will likely get two summers out of each set of summer tires so an extra $160 every two years over 10 years ($800 more total in tire costs) just doesn't make sense to me.
SGT_OKINAWA
Member
- :
- 2010 Mazda CX-7
BUZZZT! Only 1/2 right... TAKE A LOOK HERE
See there are TWO Premacy there and multi-sub level trims. (usa)
Your link: LINK is to the 20CS Smart Edition,
AKA: Bunny Hugger, Tree hugging hippy
crowds version (notcool) that ONLY
comes with 15" Rims.
The NORMAL Premacy can come with
15", 16", and 17" and 4WD model,
(Awww sorry USA you don't get the
4WD version) can come with any of
the three sizes in Japan.
ALSO if you go to the CUSTOM SET
UP, you can order any size you want,
but it'll cost you TWO nuts and a foot
to buy: CUSTOM ORDER, BUT IT COSTS A LOT!
******************
Most Premacy bought over here are
the Z20 trim level and they come with
17" STOCK wheels, see middle column
on the spec sheet: 17 X 6 1/2J
(17" so tiny, I think they belong on a
go cart, muahahaha!)
Mazda Premacy Three Trim Levels,
BUZZZZT! Same as mpVue, close but no cigar,
not ONLY 15" in Japan.
Now your questions about 17",
well 17" is the universal 'all around'
tire and rim size for MOST passenger
cars. (hear ya) so it is a little of both...
ZOOM BLING, ZOOM, BLING !
-30 for doubting Mazda's intelligence
on picking the best rim tire combo for
the Mazda 5 and Premacy. (detect)(wink)
Okay, just has to add that, sorry, but I live
in the land of the RICE Premacy, don't be
aten on the Premace naaw (wink) (smoke)(cheers2)
Peace!(rei)
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- 2008 Mazda5 5MT Sport w/ Popular Package
