Will 17's or 18's raise my car?

[scott03]

Will 17's or 18's raise my car?

[BoonyBoun]

Depends on the profile of the tire.

[vvtlikick]

215/35-18 is about the only 18" tire that won't raise up your car compared to stock. There's alot more leeway in 17" tires.

[Diesel Dud]

225-35-18 is perfect stock from a GT standpoint (195-60-15)
stock GT-S tires are slightly smaller

[scott03]

ok , next question. If i do get a tire with a profile that will raise my car how will it effect performance? I'm looking to upgrade from stock gts wheels but not loose performance. I'm going to get lighter wheels, most likely 17's. What could i loose? torque, acceleration? inacurrate speedometer?

Thanks,

Scott Phillips

[vvtlikick]

For purposes of acceleration/braking, increasing wheel and tire weight/inertia will feel just like adding static weight to the car, only multiplied (i.e. +6lbs on the wheels = +20lbs static or something).

If you get a light 17" wheel with correctly sized tires, I think any performance penalty will be slight. Among 17", I'd prefer 205/45-17, 215/40-17, or 225/40-17 tires on 17"×7"or 17"×7.5" wheels with a near stock offset.

[scott03]

Could i get 17's ro 18's with correctly sized tires that would increase performance?

[vvtlikick]

If my only concern was performance, I'd get the smallest wheels that'll fit over the brakes, namely 15 inchers. If I wanted some show and go, I'd go with 16" or 17" wheels. 18" wheels are just for show.

But if you're truly concerned about performance, I'd spend more money on great tires, not pricey, super-light forged 17" wheels with crappy tires.

For example, I think there's several Celicas on this site with pricey, lightweight Volks, but they have lousy tires on them, like the Yokohama Paradas :thumbdown

[scott03]

ok, i don't quite follow you on the 15inch being better than 17inch. So why would a lower weight 17inch wheel have worse performance than a heavier 16inch, tires not taken into account. I understand ride quality might be a little rougher, but shouldn't handling increase? How would acceleration be effected, assuming the profile of the tire keeps the tire radius the same?

[vvtlikick]

Even if the 17" wheel/tire combo weighs less than the 16" wheel/tire combo and the rolling circumference is the same, the 17" combo can still negatively impact accleration and braking. Because the rotational inertia will probably still increase, even with the lighter weight.

I think the best tire size for street performance is probably somewhere among: 205/55-15, 225/50-15, 205/50-16 and 225/45-16. I don't think the taller sidewalls will compromise handling much, if it's a high performance tire.

If you weren't worried about speedo/odometer accuracy and highway cruise, you could consider smaller tires, like: 205/50-15, 225/45-15, 205/45-16, or 215/45-16.

[scott03]

by rotational inertia, you are meaning that the weight of the 17 inch is farther away from the axle than the 15 inch. Ok, that makes sense. I'm a newb at tires, could you explain how to read them. Also, am i making a bad decision by deciding to sell my stock gts wheels and tires (stock tires) to get something like these http://www.edgeracing.com/product/bundle/index.php?d=17&m=75&v=4396 or these http://www.edgeracing.com/product/bundle/index.php?d=17&m=166&v=4396. And which tires will be good and the cheapest.

Thanks,
Scott Phillips

[vvtlikick]

Don't forget, the tire weight matters just as much as or even more than the wheel weight, since a set of tires weighs just as much as a set of wheels and the tire weight is further from the axis of rotation.

But I also wouldn't worry about buying lightweight tires, I'd worry more about tire price/wear/grip/etc.

Tire sizes are pretty simple to figure out.

205/50-16 means:

the tire is 205mm at it's widest (tread width is less than this)

Each sidewall is 50% of the width (50% of 205mm = 102.5mm)

The tire is supposed to be mounted on a 16" diameter wheel, the allowable wheel width is given as a range by the manufacturer (Yokohama recommends 5.5"-7.5" wide for the stock A680 tires)

Also, note the manufacturer specified tire revolutions per mile are usually different from what you calcluate given the dimensions, I'd guess the discrepancy comes from the distortion of the tire by the vehicle weight.

In summer tires, I recently picked the Yokohama AVS ES100. And I also have Michelin Pilot Alpins for winter. Next time, I'll probably get the Bridgestone Potenza RE750 for summer, and the Michelin Artic Alpin for winter.

There are higher performing summer tires than the ones I cited, but they're expensive and generally short-lived. But what do you want? Summers? All-seasons? Winters?

[NoCones]

Originally posted by vvtlikick
Also, note the manufacturer specified tire revolutions per mile are usually different from what you calcluate given the dimensions, I'd guess the discrepancy comes from the distortion of the tire by the vehicle weight.
More likely because the tire size numbers are not that exact. What you theoretically calculate as the tire's circumference often won't exactly match the true size of the tire.

[scott03]

I live in North Carolina and the summers aren't too hot and the winters arn't too cold. I'm looking for a tire that will last a long time, whatever is normal for a tire, but its not going to hurt me performance wise. Would like to keep the same performance as stock but look better. I never got an answer to the question about me making a bad decision to sell my stocks and get one of those wheels i gave links for.

Thanks,

Scott Phillips

[NoCones]

Longevity and performance are competing goals as far as tires go. You're always going to be sacrificing, one or the other (or both) to some extent. Why doesn't anyone seem to get that?

As for whether you're making a "good" decision, I don't think anyone can really tell you that, because only you know how much you value looks, performance (which could mean any number of things), and your $$$.

[scott03]

yeah i understand that stickier, better performing tires have shorter lifespands. Maybe performance is not the word i should be throwing around, i don't race my car, although i would love to take it to the track. Of the wheel and tire packages i linked too, which tires would last the longest? Thanks for all the help.

Scott Phillips

[celicat23]

There's a tyre size calculator that easily shows you the before and after size of your new/old tires/rims. Check it out at:

http://www.miata.net/garage/tirecalc.html