mpgandco

Tim
We now own the same car.I just purchased a beautiful Artic Silver 98 C2S in Florida.You are close in Los Altos.I would like to hook up after I get my car.It was picked up today.Do they make Ps2 in the size you mentioned for the front?Will the diamters be correct for the Front and Rear?Let me know how they work out for you,Ride Quality,Noise,handeling.how much taller is the 295/18 to the 285/18?

mpgandco

Tim
Here is a photo of my unrestored BMW Factory Turbo
http://forums.rennlist.com/upload/dsc01170_medium.jpg

David in LA

Yes, TGP's comment is what I was referring to....wheel size and offset are a separate issue and there is no difference btn C4S, TT and C2S - although a WB will have more options than a NB. With a 4WD IIRC the circumferences need to be +/- 3% differences max whereas (aesthetics aside) you generally have more possible combinations w/a 2WD (also IIRC you still need to be aware of size impact on ABS functioning, etc. With the 315s rear, what size are you running up front?

Does anyone know what is the maximum width you can run up front (I have 245 and there seems to be plenty of room left)? 255? 265?

David in LA

You're probably OK but IIRC that size combo is pretty close to the max size difference for a C4.

TGP

First time posting a picture so I hope this works. We had a break in the weather yesterday so I finally got my new tires and wheels mounted on the car.

No fitment issue with the 295/30 on the rear. In fact plenty of room even with the ROW set up (done by Viper Bob). Same is true for the 235/40 up front.

Ride quality seems fine with only minor change from the 17" wheels and tires. The front of the car seems much more stable at turn in with the larger tires which is refreshing. Rosd noise is an improvement however my rear tires were shot so it is really an apple to orange comparison.

I did weigh the rear tires before installing as that question always seems to com up here. Looks like the 18"/PS2 set up is about 8-9 lbs heavier than the 17"/P-Zero set up on the back. I did not do the front - forgot.


mpgandco - Yes twins! Coffee or lunch sometime would be great or you should look out for a BAR drive.

mod4b

Where did you have your tires mounted? Cost? I work near San Mateo and need new rears

mpgandco

Tim
What ba difference the 18's made on your car.Now it looks as it should.Keep me posted on the PS2's.Are they pretty quiet?

Jukelemon

Don't follow.

What do you mean?

TGP

I had them done at Wheel Techniques in Santa Clara (near the SJ airport). They refinished the wheels and did the mounting. Did a great job on both.

CarmG993

Can one run 225 on 18x8's on front and 295 on 18x11's on rear on a C2S with no issues?

Father of 3

I think what he is saying is that because of 4wd, there is a maximum wheel circumference differential that can exist or else the computer sensors that shift torque between the front and rear will be affected. Either that or he thinks it will just look weird

TGP

Don't know about 18x11 but as shown in the picture I am running 235/40 on the front and 295/30 in the rear on stock Technology (Hollow) rims and ROW M030 with no issue.

Hope that helps.

David in LA

It's the former...you've seen my tire/rim set up so you know I have nothing against "weird".

Junkelman - Fo3 is correct...for 4WD 993s the ratio of the rolling circumferences (and hence diameters) between the front and rear wheels are not supposed to be different by more than 4%. There are a few threads on this topic that go into the issues in greater detail...I do not have any personal experiences w/4WD 993s (both of mine are 2WD) and so am OK w/running "weird looking" combos ( )..but if I ever find my 993TT this would be a high priority for my tire/rim selection.

Martin S.

I ran a mismatched set one on my 993...a set of 205s on the front, 255s on the back...I must have gotten them cheap. The rolling radius differential was excessive, by X%, and it shut off my ABS...not cool. I immediately changed tires to factory specs...and the problem went away...of course I flat spotted the fronts..they were junk. <<<Advice for me...

PierreTT

Folks,

I recently bought a set of wheels (8X18 & 11X18) I cant fit stock size tires at the rear wheels anymore (11 instead of 10...) so I have to go to 295/30-18 instead of 285/30-18.

I was going to keep the front size stock (225/40-18) but when I read this thread, I realized that I should also enlarge the front tires as well to avoid issues with my AWD system.

I then downloaded the Excel spreadsheet made my 993 Pilot (Thanks, great tool) to verify my toughts...

I'm a little confused now. The "Actual Front/Rear Rolling Circumference Difference " is less with the original 225/40-18 than with a 235/40-18 when I use a 295/30-18 at the rear...

Some guru can explain me why? ...and what front tire size should I put on my car if I have 295 at the rear...

Hope it also helps the other AWD guys here...

Pierre