dlr944

I running Toyo Proxes T1-S on my 89 951

Front 205/50 17" 7mm of tread depth
Rear 255/40 17" 3mm of tread depth

Appears that the front tread is in good shape roughly 7mm. However, the rears are in need of replacement 3mm.

Of course I perfer to replace all four, but can I replace just the rears given the tread depth on the fronts? Suggestions please?

If I replace all 4 tires, I plan to use S-03 pole postions.

pete944

I wouldn't use different brands on the front & rear. The car could get unpredictable. If you just replace the rears, stick with the Toyo's. If you want the S-03's, get all four.

Jamie944

ditto:

Jamie944

I think I am becoming a post *****. LOL never had a one word post before.

adrial

What kind of weather do you drive in? If its mostly dry weather, I wouldn't worry too much about running different tires front vs. rear. It really depends on how you drive and your experience level IMO.

sweanders

Why do you plan on changing them already? A new tire is usually 8-9 mm's and you don't really need to change them until they are down to less than 3 mm's. When driving on dry roads you'll probably have the best grip when they are around 2-4 mm's..

SimonK

Don't mix - car will feel awful with all new tyres for a while (tread depth) - you are being warned - it will be especially noticeable if you only change rears. You will have great front bite and rears will sway like mad - Grrr, I hate that.

See: https://rennlist.com/forums/showthre...threadid=78406

Verruckt

When you are ready, go with the SO 3 pole position tires... you will not be disappointed. They are great in the dry, and amazing in the rain.

dlr944

Not planning on running two different brands of tires. Either replace the rears with the same brand as the front (Toyo Proxes) or replace all four with S-03's.

Essentially, the rear tires have very little tread left and the fronts look pretty good. Since you can't rotate tires (front to back), the rears will wear faster if you are boost freak. So what do most owners do? Replace the rears as needed or replace all four at the same time? Don't want to waste money on replacing the fronts if it's not necessary - but I'd like to get a second opinion.

Thanks

Florida951

You're fine, I dont think i even have 2mm. Wet grip is still ok as long as it doesnt rain too much, then just think loose gravel. Great fun!~

SimonK

Our cars tend to go through 1 set of fronts = 2 sets of rears - just keep the same brand.

Why are you running 205/50/17 @ the front? You should be running 225/45/17 fronts and 255/40/17 rear. Your car must under-steer more due to your 205 fronts.

dlr944

Interesting. The PO had the wheels and tires installed by WheelSource in Dayton OH. My understanding is they race 944s and are very familiar with these cars. I am not sure why they chose this setup?

Are you suggesting that I should increase my contact patch and lower the front tire profile given the size of the rears? I have not experienced a lot of understeer - more oversteer than under due to boost kicking in with lower tread rears.

My understanding is that there is only a 1/10 of inch difference between the two sizes and will make little difference. Is there a rule of thumb?

Chris_924s

Go Jamie, Go Jamie.. Be a post *****, Be a post *****!

I'm at the replacement phase- new tires before the end of fall. The 924s has 195/65/15's all around- Eagle LS's. I like them for all season driving.

I'd LIKE to replace them with Michelin Pilot XGT V4's 205/65/15's. - I had them on my Mitsu GT and loved them- great in dry/ wet/ sloppy / snowy conditions.

problem is I cant find that size anymore. they have that size in an Pilot HGT H4. aside from the speed rating and price I dont see any difference..
89$ for the H4, 124$ for the V4.. Big difference~!

any comments??

SimonK

''Are you suggesting that I should increase my contact patch and lower the front tire profile given the size of the rears? I have not experienced a lot of under steer - more over steer than under due to boost kicking in with lower tread rears.''

Let's just talk tyres not boost kicking in for a moment.

I presume you have 89/951 which is an S model. Stock, this car was shod with 215/60/16 front and 245/55/16 rears here in Europe.

If you went 255/40/17inch at the rear, you should go up the same % @ the front in order to keep it balanced = 225/45/17.

You would have more of an under-steer mainly because your front tyres now have less of a grip versus proportionally wide rears with more grip = ploughing on straight through corners when on the limit. If you increase the front width, tyre will have more grip and will tend to bring what will seem to you now - more over-steer into play - more grip front = happier tail but also = the way your Porsche was set up stock.

So your car is now not quite stock but safer and less demanding to drive. But at the same time - and you won't like this - your car is also slower if you are a pro!

PS. Your current 205 is less than stock set-up on your 16 inch wheels.

dlr944

While the width is reduced from 215 to 205 the aspect ratio was lowered from 60 to 40. So less sidewall flex = better cornering. But your right, the contact patch may be smaller - assuming the offset wasn't changed from 16" to 17".

I appreciate you pointing this out. When I replace all fours, I will take your advice and use the 225/45 up front. Man, without the Rennlist what would one do.....