Ideal Offset? 15x7 ET42 Wheels

[TRD_Yaris]

I'm hoping that some people out there have atleast some experience with the best offset for performance. I'm looking to buy Falken Hanabi 15x7 wheels, and they have a 42 offset. I still don't totally understand offsets, nor do i have much experience with the Yaris so could somebody let me know if this would be an ideal wheel?? I've been recommended 205/55/R15, but i might just go with 195/60/R15 (or maybe 195/55/R15 for a bit better gearing and more likely to fit under a lowered suspension)..

thanks guys!

[SophieSleeps]

I think you should choose what way you want to go with your car first.

If it's performance that you want...there are several types.
For speed, a wider tire and bigger wheel will actually slow you down.
For handling a wider tire will help you grip the road if done correctly.

Wheel/tire size has nothing to do with gearing. Your overall wheel/tire diameter should be the same.

As for offset, that's simply for fitment purposes. A higher offset sits further into the center of the car. A lower offset pushes the wheel out the opposite way.

[TRD_Yaris]

actually, overall gearing is affected by tire profile..but that wasn't the main reason i was going with those tires..partially it was about not wanting to go so wide as to hurt fuel efficiency from the extra road friction

i was more asking about a good offset for the Yaris specifically..maybe from a few people that have run 15x7 wheels....

[SophieSleeps]

Originally Posted by TRD_Yaris

actually, overall gearing is affected by tire profile..but that wasn't the main reason i was going with those tires..partially it was about not wanting to go so wide as to hurt fuel efficiency from the extra road friction

i was more asking about a good offset for the Yaris specifically..maybe from a few people that have run 15x7 wheels....

Oh. My bad. Thought you were asking something different.

Hey, I don't mean to get off topic, but can you explain what you mean by overall gearing? How does tire profile affect it?

[silverRS]

Im looking at getting a pair of SSR 16's in gunmetal for mine. Not to big not too small.

[Ron]

Originally Posted by SophieSleeps

Hey, I don't mean to get off topic, but can you explain what you mean by overall gearing? How does tire profile affect it?

the bigger the overall diameter of the wheel/tire combo, the more physical distance the car travels for every revolution of the axle.

so a 205/55/15 tire would net a similar effect as a slightly higher final drive, than say a 195/55/15 or 195/50/15 tire.

fyi, the yaris has a slighly shorter final drive ratio than the older echo

i personally have upsized my tire sizing a bit, to get the taller gearing because i dont really care about the get up and go acceleration of the car, but the difference is may be 4%. so not that much of a difference at all.

[JDMVitz]

Does anyone know what is the stock offset for the Yaris?

[why?]

175/65 R14 = +39
185/60 R15 = +45

[SophieSleeps]

[B]

Originally Posted by Ron

the bigger the overall diameter of the wheel/tire combo, the more physical distance the car travels for every revolution of the axle.

so a 205/55/15 tire would net a similar effect as a slightly higher final drive, than say a 195/55/15 or 195/50/15 tire.

fyi, the yaris has a slighly shorter final drive ratio than the older echo

i personally have upsized my tire sizing a bit, to get the taller gearing because i dont really care about the get up and go acceleration of the car, but the difference is may be 4%. so not that much of a difference at all.

Yeah, I understand that. I don't think that's what TRD_Yaris is talking about.
When you buy wheels you have to get as close to the same overall diameter otherwise your speedo/odometer will be off.

TRD_Yaris says that the tire profile affects gearing and I'm not understanding what he means.

Originally Posted by why?

175/65 R14 = +39
185/60 R15 = +45

Proper offset is dependent on wheel width.
You should include with width of the wheel when stating offset.
A 8" wide on a 45 offset is 6mm different than an 8.5" wide with a 45 offset.

[Ron]

Originally Posted by SophieSleeps

[B]

Yeah, I understand that. I don't think that's what TRD_Yaris is talking about.
When you buy wheels you have to get as close to the same overall diameter otherwise your speedo/odometer will be off.

TRD_Yaris says that the tire profile affects gearing and I'm not understanding what he means.

The way i explained tire profile and gearing is the only way that it can be possible, and yes, it does result in the speedo/odo being off. But like i mentioned, unless you upsize or downsize significantly, the speedo/odo calibration will only be off by a bit, usually less than 5%.

[heylookitsjames]

The lower the offset you go with on yor car, the wider the track will be, and therefore there should a theoretical increase in handling ability of the car. however, if the offset is too extreme on the front wheels, it can cause the scrub radius to spike, basically nulling all benefits derived from the decrease in offset.

All that aside, I wouldn't got lower than +25 on a 7" rim in general for FWD applications. I plan on running 15x7.5 RS Watanabe cyclones with a +24 offset. Anything under a 20 will make you look like a low rider anyway.

[SophieSleeps]

Originally Posted by Ron

The way i explained tire profile and gearing is the only way that it can be possible, and yes, it does result in the speedo/odo being off. But like i mentioned, unless you upsize or downsize significantly, the speedo/odo calibration will only be off by a bit, usually less than 5%.

That's why I asked him the question.
If your choosing the correct tire size...how do you affect gearing.

[Ron]

Originally Posted by SophieSleeps

That's why I asked him the question.
If your choosing the correct tire size...how do you affect gearing.

'correct' is subjective... some people care more about the gearing effects of the tire sizing/profile, and not as much about how accurately the speedometer is reading. if the overall diameter of your tire/wheel combo is the same as stock, the speedo will not be affected, nor will the gearing. different strokes for different folks

[SophieSleeps]

Originally Posted by Ron

'correct' is subjective... some people care more about the gearing effects of the tire sizing/profile, and not as much about how accurately the speedometer is reading. if the overall diameter of your tire/wheel combo is the same as stock, the speedo will not be affected, nor will the gearing. different strokes for different folks

Agreed.
I don't think you can affect gearing if you get the same overall diameter.

There's more than just gearing when changing overall diameter. If you have an auto Yaris, it affects your shifting as well.

[TRD_Yaris]

Originally Posted by Ron

the bigger the overall diameter of the wheel/tire combo, the more physical distance the car travels for every revolution of the axle.

so a 205/55/15 tire would net a similar effect as a slightly higher final drive, than say a 195/55/15 or 195/50/15 tire.

fyi, the yaris has a slighly shorter final drive ratio than the older echo

i personally have upsized my tire sizing a bit, to get the taller gearing because i dont really care about the get up and go acceleration of the car, but the difference is may be 4%. so not that much of a difference at all.

yes, this is what is was talking about as far as "overall" gearing being affected by tire profile. What i mean is that : IF your stock tire size is 195/55/R15 (for example), then if you changed over to 195/60/r15 or even 205/55/R15 the then you are actually changing the overall length of travel for every revolution of the wheel/tire..meaning your speedo will be off and even if you got better gas mileage, you wouldn't see it unless you accounted for it

simple explanation: basically, if you took a tape measure and wrapped it around the tire along the tread..you would find the 195/60/r15 and 205/55/r15 are a bit longer than the stock 195/55/r15 's tread length..