Spacers would not be useful in anyway unless it was to clear some component where there might be contact or rubbing, or maybe just for cosmetic appeal.

And nothing would or could stop you from using a certain rim unless you could not get a tire to match the requirments of your drive line.

Tires makers are allowed to have a variance of up to 7% from described manufactured size and withing the line. Now most of them do not varry by anywhere near that much but there are differances.

I have help customers build a few Bonneville salt flat racers where we ground and resurfaced tires to get matching diameters from left to right and even front to back because at speed the differances can really mean the differance between winning or loosing or even crashing in a firey blaze.

 

Today i noticed washing my car that my Pilots Sports are N3 rated at the front and N2 rated at rear. Does this make any difference?

 

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=26

Read this, I think it will explain it for you.

 

Im really sorry if this has been discussed but I'm trying to figure out something. Im looking at a 2004 996t that has the 997t wheels. I saw this thread and asked the dealer to give me the tire size on the car.

front: 235/35 zr19
rear: 305/30 zr19

will these cause a diff problem? guy said the car comes with OEM wheels and tires but if damage has been done with these wheels on the car, then I'm running to next car...

I really like the look of the wheels but understand they may be causing a serious expensive problem.

Advice??

 

Ask the dealer to tell you the make and model of the tires as well, then go to tirerack and search for that exact tire.

When you go into the specific tire's page just click on the tap below that says "Specs" and one of the columns there is "overall diameter". The overall diameter is what counts and what should be considered, that number cannot vary (from what people say) more than 1% from the original tires overall diameter.

Hope this helps.

 

ok just got off phone with dealer... here are the specs

front: diameter = 25.5 and 817 rev per mile
back: diameter = 26.3 and 788 rev per mile.


thoughts?

 

I myself would go with a 245/35-19 front and 295/30-19 back; that would put you closer to matching ratios. This is a very acceptable match for a 996.

245/35-19 --> 25.8" 807 rev/mile
295/30-19 --> 26.0" 799 rev/mile

 

ya i would too but this car has already has the sizes (f=25.5 and r=26.3) on the car. From what Im reading, this could cause serious damage to the drivetrain. Who knows how many miles of the 38,000 had this set up?

sounds like I should pass don't you think?

 

Well if Porsche spec's that then I bet they know the car can take it. Unless the 997's have a slightly different diff ratio front to rear and this is what they do to adjust the ratios to equal. Maybe one of the other peeps here know better on that fact.

I myself would call one of the good tuner shops on this sight and I bet they would be able to shed some more light on the issue. I am a good mechanical engineer with Das Auto's but I am no Porsche Guru.

 

oh i should clarify, the dealer I am talking to is a Lexus dealer. they took the car in on trade. I explained that I had a concern with the different sized tires on front vs rear and they looked at me like I was speaking a different language.

With what Im readying the rear height is off too at 26.2.

Its stuff like this that make you go...hmmmm

Thoughts on if this car is too risky?

 

+1. Getthe right tire sizesand you are good. Those are the sizes i run with this setup.

 

No spacers needed, just get the right size tires mentioned already!

 

Mike

Your input on the previous threads were very helpful. Can you clarify what tire sizes / brand you are currently using.

Thanks

 

in my search, I uncovered that the tires (doesn't really matter wheels) on the car currently are NOT good for the car. there is too much of a difference between the rotations from the front and the read. In my readings, posters have noted that this can cause a serious problem with the drivetrain of the AWD system.

NO question, I could buy the car and fix the problem with the suggestions I'm getting from the above posters (thank you!)

THE real question is, with the car having 30,000 plus miles, I don't know when these tires (of which we have determined are NOT good for the drive train) were installed.

So back to my original question that being, should I still consider this car? Not knowing how many miles were driven and potentially burning up the AWD drivetrain?

again, no question, I can fix and pretty easy fix indeed, but the real question is has the damage already been done and would you still buy the car?

hopefully that clears up my question on if I should walk away or still consider the car

thanks everyone! sorry for the confusion

 

315/25/19 is the only size you can use on the rear (which sucks b/c they are limited in availability and expensive. Invos and Falkens are probably best value, not sure if Toyo makes this size anymore). Other sizes are either too tall and will rub or cannot match properly to the front.

For the front, you can use 235/35/19 or 225/35/19.

Ideally, you should use 225/35/19 on the front and 315/25/19 on the rear becuase both of those are exactly 25.2'' in height, which fits perfectly without rubbing, without need of spacers, and is the same rotational value (given the same overall height/diameter).

I've been running 235/35/19 and 315/25/19 on my car and I think the slightly differernt size is what was causing a PSM issue on high speed corners last year. The problem has gone away awhile ago now that my tires are more worn, but I think the initial (although slight and within spec) height difference was making PSM activate annoyingly around high speed corners when it shouldn't have. I know the PSM issue here affects many with 19'' wheels, but not everyone.