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I looked around, but I couldn't find the answer.
I just got the rear tires replaced with a 305 wide, and I was wondering if this tire is going to use the same amount of air (36 psi) than the 295?
I would appreciate any advice.
 

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Yes, Mine came with 305 and door shows 36
 

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Yes, Mine came with 305 and door shows 36
RS4Cab, but if you read the sticker in the door, does it say 295 or 305 for the rear tire width? 295s are the standard tire size and they use the 305s on the polished and titanium colored wheels. It would kind of surprise me if they had a different sticker for the wheel options.

I am sure that both tires actually use the same pressure. They are the same brand & model of tire and very close to same load rating (295 are (100Y) & 305 are (102Y)). Tire pressures are also really a range which depends on the road conditions and driving style. So, setting both back tires to 36 will work fine for normal driving.
 

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RS4Cab, but if you read the sticker in the door, does it say 295 or 305 for the rear tire width? 295s are the standard tire size and they use the 305s on the polished and titanium colored wheels. It would kind of surprise me if they had a different sticker for the wheel options.
Surprise:eek: Just went and looked and sticker does show as 305. I run both front and rear about 2 lbs more
 

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I forget,what are ideal tire pressures for top speed straight line runs and for extreme cornering ?? the same as on door sticker...I think not.:) What size front does SDR8 run? a 265 or 245?
 

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What size front does SDR8 run? a 265 or 245?
I went with 245/35ZR19 (93Y) up front, when I went from 295 to 305 in the rear. It is just a simple 1 cm wider on all four corners. I know the 245s are not a stock size, but they work fine. I know it does make the diameter of the front tires a tad bit bigger than any stock tires, but I did get confirmation from Audi that it should not cause any problems. The variance is in their range of acceptable differences.

The stock 235s are (91Y) so the 245 at (93Y) are close enough. They can carry a tiny bit more load, but not a big change from stock design.

The higher the number the higher the load index (load carrying capacity). The number and Y inside the parentheses means speed rated is in excess of 186 mph (highest speed rating they have so far).
 

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Is there a measurable difference in 235 245 's height ??
 

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Is there a measurable difference in 235 245 's height ??
it depends on the aspect ratio: the # after the width is height as a % of width, so:
a 245 is 10 mm (1.0 cm) wider than an 235; a 245/35 is 35% higher than a 235/35 or about 3.5 mm; so its diameter is 7.0 mm greater and its circumference 3.14 x 7.0 mm or about 22 mm; so the 245 rolls a little less than an inch further on each revolution--not very sigt. in a circumference of about 67 inches; your speedo might read 1.2% slow!:rolleyes:

a great little handy tool for looking at wheel/tire size questions and problems is at Wheelsmaster:http://www.wheelsmaster.com/rt_specs.jsp
 

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Is there a measurable difference in 235 245 's height ??
There is not much of a difference, as willyjp said. I would not run out and replace the 235s just because the 245s fit and were a little wider. I did it because I needed a new set of tires to go with a new set of wheels and I wanted a little wider front. I also liked the idea of a tiny bit more rubber sticking off to the side to protect the rim that much more, in case someone else was driving my car and they got too close to a curb.

I am not sure where the car gets its speedometer reading from, drivetrain for front or rear wheels. Either way, since I stepped up 1 cm all the way around, my speedo should be off by around 1% (and will become less as the tires wear down).

The change is very insignificant, but if someone needed new front tires, it is worth knowing that this size is an option. As for handling differences, you can get more noticeable changes by varying tire pressures or different tire compounds. But every little bit does help...
 

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That's what I needed to know. Approximately 1/4 inch raise in front which I could use. (scraping) . BUT ,can I use the 245 with the 10mm spacers I have?? Height increase in rear with the 305 as well?? Will report...Will go with 305 in rear too, if possible with10mm spacer. Will decrease down force in rear a bit and am desparately trying to figure how to disable the stock rear wing. Linkages are complicated so am considering 'Disabling the button/switch?" Fuse info shows no dedicated fuse for wing.(DARNED IT! ). If I can pull it off ,it will be a badder ass ride.and if I can still put springs on I would be in 7th Heaven. ...Then a good alingment and camber adjusment and I should be trak ready.Whew...Many new threads here. :)
 

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...Approximately 1/4 inch raise in front ...
It actual only raises the car 1/2 of that. Only one of the sidewalls raises the car. So it should only be 3.5mm (which is close to 1/8") for the front. Not really enough to make much of a noticeable difference.

And for headlight difference, if you are going 1cm wider and staying with the same 30 series for the rear, the the front would only be .5mm higher than the rear. That is very minor and would not effect your lights.

As for your down force, all the changes are so small and the speeds we see in the US, it is not going to be noticeable.
 

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My downforce changes are mainly for carving/playing around in the canyon. :) For now.
 
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