Author Topic: Can I use two 15" rims and two 16" rims? (Read 1695 times)

aalex · « **on:** April 26, 2005, 08:52:04 pm »

My situation is this- I have two 205/60/15 tires which have at least 80% threadlife left, and 2 other tires which need to be replaced soon. I also noticed 2 rims which are still very good, but another 2 rims are in not good condition.

My question is.. can I swap two new 205/55/16 tires with 16" rims for the rear, and keep two 205/60/15 for the front? Maybe 1 or 2 years later, I will swap the other 2 to 16" tires/rims.

The tires widths are almost the same, and the new tire overall diameter is about 0.2" bigger.

Will this cause any problems regarding safety? Have anyone tried/experienced this?

morty · « **Reply #1 on:** April 27, 2005, 01:52:53 am »

Not something I recommend. Problem is you have the tires on the front handling far differently than the tires on the rear. This causes dangerous handling characteristics and can result in the rear end braking loose unpredictably. It may seem like you are saving some money, but at what cost.

There are a few instances where cars do run different front and rear, but the suspension has been set up to accomodate the alternate diameters.

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articsteve · « **Reply #2 on:** April 27, 2005, 09:09:20 am »

Try is thing:

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

Depends on the car; fwd or rwd? AWD is a definte NO!

Are these rims made of the same material?

mis3 · « **Reply #3 on:** April 28, 2005, 08:18:07 pm »

Many cars come with staggered setup with bigger tires in the rear. My 2004 CLK320 Coupe is one example.

So, do you think that the suspensions of my car's front and rear are setup differently?

articsteve · « **Reply #4 on:** April 29, 2005, 11:34:34 am »

Some cars come with wider tires on wider rims on the rears in relation to the fronts, but as for using different diameter rims that is news to me.

cloud7 · « **Reply #5 on:** April 29, 2005, 12:54:10 pm »

some high performance sports cars do come with different diameter rims... For example, I think the Prowler had different front and rear diameter rims.

articsteve · « **Reply #6 on:** April 29, 2005, 02:03:34 pm »

Prowler was not high performance nor was it a sports car. It was a GM theme car. Name another main stream production car that uses staggered diameters on the wheels.

rallytopaz · « **Reply #7 on:** April 30, 2005, 03:21:02 am »

Articsteve: The Prowler was built by Chrysler. Chrysler has never been owned by GM.

As far as other production cars that use staggered diameters, off the top of my head, the 2006 Corvette Z06 comes stock with 18x9.5 front, and 19x12 rear.

capriracer · « **Reply #8 on:** April 30, 2005, 08:35:36 am »

I think the question about stagger was:

Do vehicles that have different tires front to rear have different suspension setups than vehicles that don't.

The answer is yes - the springs, shocks, and sway bars are all spec'd based on the tire spring and damping rates and changing tire sizes changes those rates.

BTW, different diameter wheels front to rear (when the original's were the same) is a tire guy's worst nightmare. If something bad happens, you can be sure the lawyers will go there first.

Hope this helps.

aalex · « **Reply #9 on:** April 30, 2005, 07:02:28 pm »

Wow, thank you for all the replies and comments!

So it seems none of you fellows have tried this approach, so I guess it would be smart for be not to take this risk. Actually my rims are still OK to run, just does not look too good.

Therefore, I will probably be purchasing proper matching tires from TireTrends again later.

articsteve · « **Reply #10 on:** May 01, 2005, 12:07:46 am »

Articsteve: The Prowler was built by Chrysler. Chrysler has never been owned by GM.

True enough. For some reason I just associated the auto only Prowler with the pukey V6 as a GM thing. Somehow I associate it with the Chevy SSR. Still a theme car. However, 2006 ZO6 is not a "main stream" production car. Name another.

For the purposes of this discussion all that matters is that the overall diameter is close. AWD needs to be right on or you can get transfercase problems.

This dicussion is so lame because the vehicle is unknown; FWD or RWD? What is the risk if the overall diameter is 5mm difference? What technically can happen that is so bad?

capriracer · « **Reply #11 on:** May 01, 2005, 07:48:59 am »

OK, I'll bite.

The spring rate a P205/55R16 can be as little as 25% greater, but as large as 150% greater than for a P205/60R15.

So imagine what the effect on the vehicle will be if the springs were changed by this amount - but only on one end - the oversteer / understeer characteristics will be completely altered.

Sure, the guy could drive around town all month without ever encountering a situation where he even knows what the understeer characteristics are like.

But the first time he slams on the brakes, or tries to avoid a dog that's running into the street, it will be too late. He'll either drive straight into whatever he is trying to avoid - or have the vehicle swap ends on him and all the control that comes with that situation.

It doesn't matter much if the vehicle is FWD or RWD. All the work done by the vehicle manufacturer adjusts the handling characteristics so they are within a resonable range. What we are discussing here is the amount of change front to rear - and it's HUGE!.

Hope this helps.

articsteve · « **Reply #12 on:** May 01, 2005, 04:12:15 pm »

Good points, but what about unsprung weight; as in what different rims is he using: alloy v. steel.

This is a typical CD question that lacks so many details. If I was in survial mode I would not hesitate to drive with the stated tire combo. I drive vehicles in worse circumstances than that.