Question regarding tire sizes

[Reload]

I have an opportunity to pick up a set of winter tires and steel rims for a pretty cheap price but wanted to make sure they'd fit my car.

So I'm here to ask the automotive experts at Terb.

Just to let you know, the rims that are being offered are from the same make, model, and year as my car. However, they are different size rims.

I am currently using the following tire size:

235/55R18 (Aluminum rims)

The tires being offered (including steel rims) are the following tire size:

255/60R16 (Steel Rims)

Now I'm currently riding with a set of 18" rims and the ones being offered are 16" rims. I did take a look at one of the tires that is being offered and it seems like a higher profile tire than what I have which, I imagine, should give it give it the same overall diameter as my tires? It's a smaller rim but with a higher profile tire than what I have.

So would the tires that are being offered work for me?

This also brings me to my next question.

My vehicle has the TPMS system which has sensors in each of the tires to monitor the tire pressure and warn me if any of my tires are running low on pressure. Now if I do purchase the set of steel rims, I don't want to spend a crapload of money putting sensors in the winter tires as well as having to get the vehicle re-calibrated to the new tires when I have them changed which is twice a year as I'm sure this could get really expensive. Is there a way to slap on the winter tires without the warning light going off in my dash telling me I've got tire issues because the actual tires with the sensors in them aren't on the car?

 

[TRX]

that's the closest diameter to your current set up which does'nt affect much of your speedo. here is the link for tire size calculator

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

the only problem if you use the 255 wide tire is less effective in winter tire

 

[papasmerf]

It's all about the bolt pattern

 

[TRX]

It's all about the bolt pattern

he states from the same make, model, and year as his car.

 

[S.C. Joe]

un, the make and model car?

I do know some GM cars go by tire speed. Like if both tires-the back or the front-turn at the same speed, its thinks everything is OK. Guess the thinking is, both tires will not be going flat at the same time.

When 1 tire has different air pressure-one tire is at 30 psi, the other has 25 psi-the tires rotate at different speeds. Not much but the computer can tell and sets the warning light. So as long as both front tires or both back tires are the same sizes and set at the same air pressure, everything is cool. This is just with GM cars, like the Buicks. Not sure if all cars are like that or not.

Did the 18" wheels come from the factory? If so, the 16" wheels may very well hit the brake rotors. Also the bolt patterns might be different. I say its a good chance 1 or both will happen. Highly unlikely they even bolt on-unless the car came with 16" wheels from the factory-but maybe. Sometimes the same type of car gets different size wheels depending on the trim package.

If you can, bolt one wheel on and see if it fits, but these newer cars don't have much room to spare for a taller tire.

Your speedometer will read slower with a taller tire too.

 

[papasmerf]

he states from the same make, model, and year as his car.

worth a look
count the bolts and make an offer

 

[S.C. Joe]

worth a look
count the bolts and make an offer

Even if the number is the same, the spacing can be different . A Ford has a different spacing than a GM wheel, even thou both might have 5 studs. Some are 4 1/2", others are 4 3/4", then some are even Metric

 

[papasmerf]

Even if the number is the same, the spacing can be different . A Ford has a different spacing than a GM wheel, even thou both might have 5 studs. Some are 4 1/2", others are 4 3/4".

we are assuming the same make and year car.............

Check out the Lazer eye surgry thread

 

[S.C. Joe]

I need to slow down when I read

 

[papasmerf]

I need to slow down when I read

me too but it takes all the fun out of it

 

[shakenbake]

My one concern would be that they usually recommend a narrower, but higher profile, tire for winter use.

 

[S.C. Joe]

Also sometimes everything can be different even with a same make, model and year car.

Like a 4 cylinder engine model will get smaller brake rotors, than a 6 cylinder car would. Thats why the wheels are bigger, so they fit over the rotors.

Sometimes they just have a heavy duty brake option, which calls for a larger wheel.

 

[Reload]

un, the make and model car?

I do know some GM cars go by tire speed. Like if both tires-the back or the front-turn at the same speed, its thinks everything is OK. Guess the thinking is, both tires will not be going flat at the same time.

When 1 tire has different air pressure-one tire is at 30 psi, the other has 25 psi-the tires rotate at different speeds. Not much but the computer can tell and sets the warning light. So as long as both front tires or both back tires are the same sizes and set at the same air pressure, everything is cool. This is just with GM cars, like the Buicks. Not sure if all cars are like that or not.

Did the 18" wheels come from the factory? If so, the 16" wheels may very well hit the brake rotors. Also the bolt patterns might be different. I say its a good chance 1 or both will happen. Highly unlikely they even bolt on-unless the car came with 16" wheels from the factory-but maybe. Sometimes the same type of car gets different size wheels depending on the trim package.

If you can, bolt one wheel on and see if it fits, but these newer cars don't have much room to spare for a taller tire.

Your speedometer will read slower with a taller tire too.

Sorry.

It's an 06 Rav4.

They come with tire sizes ranging from 16" to 18" depending on the trim you're getting.

I got the Sport which comes with 18" rims.

The base comes with 16" steel rims, and the Limited comes with 17" aluminum, I think.

My 18s came factory with the car and have a rated tire pressure of 32psi.

I would be buying an entire set of 4 tires and rims which are identical. So when I swap between winter/summer tires, I'd swap all four.

So with the differences in the tire specs, would I expect to see an issue with the odometer reading when I swap tires?

 

[onehunglow]

Go to your mechanic first and run it by him. If you have ABS your ABS computer might have a nervous breakdown. It will sense that there is a difference, not know you have altered the tire size and breaking may be affected. Do it yourself and have an accident and it may affect your insurance coverage and responsibilities. I wanted to put bigger tires on my truck, just one size bigger and the dealership and my mechanic said that we would have to enter some code into the computers to let them know that the tires have changed. Affects ABS, transmission-odometer, sensors etc etc.

Its a big mess, see your mechanic and get the lowdown from him. It can be done but not easily or cheaply.

Best of luck.

 

[TRX]

Sorry.
I would be buying an entire set of 4 tires and rims which are identical. So when I swap between winter/summer tires, I'd swap all four.

So with the differences in the tire specs, would I expect to see an issue with the odometer reading when I swap tires?

with the set of tires and rims you are planning to buy, based on tire calculator when your speedo reads 100 kph you are actually travelling at 99.5 kph

 

[S.C. Joe]

You can live with that.

I would ask a tire shop what they think. The dealer always makes everything a bigger deal than it has to be.

 

[SELECT COMPANY]

You shouldnt have any problems. As for the TPMS sensors, your car's computer will know that there are no sensors in the rims so it will turn off after a certian amount of time. It turned off on my car after 20 min. When I put the originals back on the computer sensed them and it was operational again. Some vehicles will require that you go into the dealership so they can turn that feature off.

 

[Hard Idle]

This is THE definitve online fittment tool:

http://www.rims-n-tires.com/rt_specs.jsp

It gives you a side-by side comparison of all the data (as well as diagrams showing effects on offset and wheelwell clearence in the case of rims.) *Make sure to Un-check the wheel/offset calculator if you don't have width & offset specs to input.

Generally speaking, differences of up to 3% from OEM are considered negligible (although in reality, going lower in height can only improve performance & safety - it would just mean a tougher ride and more risk of rim damage)

In the case of 235/55/18 vs. 255/60/16 the difference is only -3mm (0.4%) in height and 0.5% difference on the speedo (slower) as TRX said it is the closest possible match.

Assuming the donor car has the same brake backage as yours, you don't even have to think about any other fitment issues. However the fact you will have a little more rubber and less rim on a tallish vehicle might make it feel a tad more mushy & tippy in the corners during enthusiastic driving.

 

[Hard Idle]

Here is a simpler size comparioson calculator (for tires only) if the rims-n-tires.com page is too slow on your browser & connection.

http://www.discounttire.com/dtcs/infoTireMath.dos

 

[landscaper]

the rim tire combination size is the important factor for the speedometer controls as long as the total diameter is the same or very close you will be fine. The air presure monitor should ignore the wheels with no sensors in them. Winter tires typically have a higher profile this makes them work more efficiently with the softer rubber compound. The 16" rims should fit over the roters just fine if the car has 16 " tires as standard the 18's you have on are likley an option.