New Wheels...Affects Speedo?
#1
New Wheels...Affects Speedo?
Hello List.
I wanted to replace the stock rims on my '91 2+2 with something a bit nicer and larger... perhaps an 18" rim.
However, in doing so, how does this affect performance? I imagine it would provide more power but require higher RPM's to attain a speed, say 60 miles per hour, than the same speed as the stock wheels. Is this correct?
Also, moving to a larger wheel, does it affect the speedo in anyway?
Thanks.
I wanted to replace the stock rims on my '91 2+2 with something a bit nicer and larger... perhaps an 18" rim.
However, in doing so, how does this affect performance? I imagine it would provide more power but require higher RPM's to attain a speed, say 60 miles per hour, than the same speed as the stock wheels. Is this correct?
Also, moving to a larger wheel, does it affect the speedo in anyway?
Thanks.
#2
no, the wheel is not the problem. The tires are.
If your wheels are larger diameter then you must buy lower profile tires so that the new tire's outside diameter matches the diameter of the factory wheels. (mainly the rear wheels)
245/45/16 is stock
using this webpage, http://www.miata.net/garage/tirecalc.html
you can see that 245/35/18 is a close match
18x8.5 minimum width for the rear
A larger wheel is heavier. Even if the overall weight matches (for a really expensive light weight wheel) the weight is further out from the center so you have more centrifugal weight. Your braking and accelerating will be slightly worse.
If your wheels are larger diameter then you must buy lower profile tires so that the new tire's outside diameter matches the diameter of the factory wheels. (mainly the rear wheels)
245/45/16 is stock
using this webpage, http://www.miata.net/garage/tirecalc.html
you can see that 245/35/18 is a close match
18x8.5 minimum width for the rear
A larger wheel is heavier. Even if the overall weight matches (for a really expensive light weight wheel) the weight is further out from the center so you have more centrifugal weight. Your braking and accelerating will be slightly worse.
#3
Thanks Bleach. That site was helpful.
I was hoping there wasn't going to be a performance hit in acceleration, but hopefully it will be minimal and not noticeable.
I'm thinking of something similar to a 350z rim, but alloy, not chrome and something with straighter spokes, not curved like the 350z.
Anyways, after the holidays, I have no cash right now anyway so I will probably put a purchase off until later in the Spring.
Thanks for your help.
--Rick
I was hoping there wasn't going to be a performance hit in acceleration, but hopefully it will be minimal and not noticeable.
I'm thinking of something similar to a 350z rim, but alloy, not chrome and something with straighter spokes, not curved like the 350z.
Anyways, after the holidays, I have no cash right now anyway so I will probably put a purchase off until later in the Spring.
Thanks for your help.
--Rick
#4
#6
don't get discouraged about it, alignment isn't that expensive most places i checked out only quoted 10-15 a tire but you will have to have someone put the tire on for you there's no way you can get that low of a profile tire on a rim without a machine
#7
Originally Posted by 300zgearhead
don't get discouraged about it, alignment isn't that expensive most places i checked out only quoted 10-15 a tire but you will have to have someone put the tire on for you there's no way you can get that low of a profile tire on a rim without a machine
Are you aware of the difference between "mounting and balancing" and an "alignment" ?
Usually alignment is one price for the whole car, even if only the front is adjustable.... they charge you as though they aligned front and rear. I suppose they can give you the specs on the rear, but most cars aren't adjustable back there.
Personally I never bother with an alignment if I change wheels and/or tires. I only do that when I have a steering issue or if I lower the car.
#9
Originally Posted by 300zgearhead
ya i do but will still have to get someone to mount the tires and ya i did get mixed up. but i've helped put tires on ones of my buddies car and we didn't have them balanced
#10
Originally Posted by Bleach
Are you aware of the difference between "mounting and balancing" and an "alignment" ?
Usually alignment is one price for the whole car, even if only the front is adjustable.... they charge you as though they aligned front and rear. I suppose they can give you the specs on the rear, but most cars aren't adjustable back there.
#12
Originally Posted by 300zgearhead
i've helped put tires on ones of my buddies car and we didn't have them balanced
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