Ideal sizes for winter tires to fit 18" OEM's?
#3
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Originally Posted by d!abolic
Can I use 225/45 for all four? If not, why, and which should I use instead?
1) If your car is equipped with TCS or VDC (and, TCS is included in VDC equipped Z’s), these devices expect a staggered height (fronts having a smaller overall diameter than the rears). If you go with the same height (overall diameter) front and rear, you may experience unwanted engagement of TCS (but that’s only the case if your car is equipped with TCS).
2) 18” wheels with snows is a poor choice. Snow tires in this class are very expensive, and do not provide the flex and traction you get with 17” wheels and snow tires for this wheel size.
3) A better wheel/tire setup for winter driving is buying inexpensive 17” wheels on which you mount Front 225/50-17” and Rear 225/55-17” tires.
--Spike
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Originally Posted by Spike100
225/45-18” snows front and rears could work, but here are some things to consider:
1) If your car is equipped with TCS or VDC (and, TCS is included in VDC equipped Z’s), these devices expect a staggered height (fronts having a smaller overall diameter than the rears). If you go with the same height (overall diameter) front and rear, you may experience unwanted engagement of TCS (but that’s only the case if your car is equipped with TCS).
1) If your car is equipped with TCS or VDC (and, TCS is included in VDC equipped Z’s), these devices expect a staggered height (fronts having a smaller overall diameter than the rears). If you go with the same height (overall diameter) front and rear, you may experience unwanted engagement of TCS (but that’s only the case if your car is equipped with TCS).
#5
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Originally Posted by d!abolic
How noticable would this be?
If you depart from the correct overall diameter stagger, you could experience a loss of power (TCS killing power to the rear/driving wheels). If that happens in the wrong place at the wrong time, it could put you in harm's way.
--Spike
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Thanks. So as long as it's 45/18 for the back, I'm fine? Or would I need 40's in the back instead if I go over/under a certain width? How about 35 or 50, are they ever used?
#10
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Originally Posted by d!abolic
Thanks. So as long as it's 45/18 for the back, I'm fine? Or would I need 40's in the back instead if I go over/under a certain width? How about 35 or 50, are they ever used?
--Spike
#13
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Originally Posted by d!abolic
Alright, and how do you calculate this?
[section width (mm)] / [aspect ratio] - [rim diameter (inches)]
For example: a tire size 225/45-18 is 225mm wide, has an aspect ratio of 45 and fits an 18" rim (wheel).
The aspect ratio (the second number) is not a measurement. The aspect ratio represents the tire's sidewall height as a percentage of the tires width (section height divided by section width). In the example above, the sidewall height is 101mm (101/225=.45).
The aspect ratio is important since that (along with the wheel size) determines the overall diameter of the tire allowing you to match your stock overall tire height (diameter). For example, a 225/45-18 tire's sidewall height is 101mm, and a 245/40-18 tire's sidewall height is 98mm. So, both tires have nearly the same overall diameter and would fit the front of a Z.
Overall diameter OEM Bridgestones Potenza RE040:
225/45 ZR18 25.9" (front)
245/45 ZR18 26.7" (rear)
--Spike
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Thanks for that explanation. So how far can I stray from these sizes? Could I put 245/40 (98mm) on the back and 235/40 (94mm) on the front?
Last edited by d!abolic; 11-19-2007 at 06:59 PM.
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No. Use this and it'll tell you the percentage error you will get on your odometer. Anything over 1% is not advisable. And both of your choices will be off considerably.
http://www.miata.net/garage/tirecalc.html
http://www.miata.net/garage/tirecalc.html
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Ok I have a couple of question:
- If I didn't want to buy 17" wheels what would be the optimal tire sizes all round for snow tires on stock 18" wheels?
- Would I actually save money buy buying cheap 17" wheels and then tires, or the perfomance just not as good? If so what would be the optimal size for a 17" tire?
- What is the best snow tire, I might have to drive the Z in the snow and choose to spare no expense (unless this will cost me more than a beater. lol)
If this is too much then just tell me to STFU!
- If I didn't want to buy 17" wheels what would be the optimal tire sizes all round for snow tires on stock 18" wheels?
- Would I actually save money buy buying cheap 17" wheels and then tires, or the perfomance just not as good? If so what would be the optimal size for a 17" tire?
- What is the best snow tire, I might have to drive the Z in the snow and choose to spare no expense (unless this will cost me more than a beater. lol)
If this is too much then just tell me to STFU!
#17
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Originally Posted by xNeo
Ok I have a couple of question:
- If I didn't want to buy 17" wheels what would be the optimal tire sizes all round for snow tires on stock 18" wheels?
- Would I actually save money buy buying cheap 17" wheels and then tires, or the perfomance just not as good? If so what would be the optimal size for a 17" tire?
- What is the best snow tire, I might have to drive the Z in the snow and choose to spare no expense (unless this will cost me more than a beater. lol)
If this is too much then just tell me to STFU!
- If I didn't want to buy 17" wheels what would be the optimal tire sizes all round for snow tires on stock 18" wheels?
- Would I actually save money buy buying cheap 17" wheels and then tires, or the perfomance just not as good? If so what would be the optimal size for a 17" tire?
- What is the best snow tire, I might have to drive the Z in the snow and choose to spare no expense (unless this will cost me more than a beater. lol)
If this is too much then just tell me to STFU!
Front: 225/45-18” and Rear: 225/50-18”
A better choice for mounting snow tires is 17” rims. Here are the optimum sizes:
Front: 225/50-17” and Rear: 225/55-17”
And, just about any true snow tire is fine. I like Dunlop and Blizzak
--Spike
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Originally Posted by Spike100
Not too much… in fact good questions. I wouldn’t recommend mounting snow tires on 18” wheels (too expensive and doesn't work as well as 17"), but if you do, this is your best sizes:
Front: 225/45-18” and Rear: 225/50-18”
A better choice for mounting snow tires is 17” rims. Here are the optimum sizes:
Front: 225/50-17” and Rear: 225/55-17”
And, just about any true snow tire is fine. I like Dunlop and Blizzak
--Spike
Front: 225/45-18” and Rear: 225/50-18”
A better choice for mounting snow tires is 17” rims. Here are the optimum sizes:
Front: 225/50-17” and Rear: 225/55-17”
And, just about any true snow tire is fine. I like Dunlop and Blizzak
--Spike
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Originally Posted by Spike100
Not too much… in fact good questions. I wouldn’t recommend mounting snow tires on 18” wheels (too expensive and doesn't work as well as 17"), but if you do, this is your best sizes:
Front: 225/45-18” and Rear: 225/50-18”
A better choice for mounting snow tires is 17” rims. Here are the optimum sizes:
Front: 225/50-17” and Rear: 225/55-17”
And, just about any true snow tire is fine. I like Dunlop and Blizzak
--Spike
Front: 225/45-18” and Rear: 225/50-18”
A better choice for mounting snow tires is 17” rims. Here are the optimum sizes:
Front: 225/50-17” and Rear: 225/55-17”
And, just about any true snow tire is fine. I like Dunlop and Blizzak
--Spike
#20
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Originally Posted by xNeo
I think I'm going to go with the 17", will 17x8 all round fit? 35mm offset? I know nothing about tires and actually read up and I just don't get them haha.
Setup 1) 225/50-17” front and 225/55-17” rear (optimum)
Setup 2) 225/50-17” front and 225/50-17” rear (all square, but works ok)
Setup 3) 225/55-17” front and 225/55-17” rear (again, all square)
Setup 1 is optimal. Setup 2 and 3 are all square allowing rotating tires and/or moving fronts to rear to accommodate uneven wear. You would think Setup 3 shouldn’t work with too tall an overall diameter on the front (especially since I have a Performance model with VDC), but it runs OK.
--Spike
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