TC101

Hi, any input is appreciated. I have the factory tires 245/50/17 on the car right now, and I will be needing new ones within the next couple of months.

I am wondering what the negatives would be by switching to 235/50/17. I know the factory rims are 8" wide.

I would imagine it would be a very negligible difference but would like some feedback from people who have experience doing it or whatever! Thanks

BDoggPrelude

I ran 235/55R17's for winter tires last season. They worked just fine. Personally, I would stick to the OEM size of you're running them year round. You have decent tire options in the OEM size. Why do you want to go to 235's?

TC101

Thanks for the response. I actually was thinking of going down to that size only because my friend has a pair of Bridgestone Potenza RE960AS PP's that have 1000 miles on them he would sell me for $400. New they are $720+, I was just hoping to get away with not spending 600-700 on tires and getting these good ones for a nice bargain!

oo7spy

Your speedometer will be 1.5% too fast, and your mileage will be 1.5% more than you have actually traveled. That is the only disadvantage.

http://www.1010tires.com/tiresizecalculator.asp

I don't want to see you in here in a month claiming you got a 1.5% MPG increase by swapping tires.

TC101

Cool, great link! I dont mind 1mph over.

M T L T L

How critical is to run tires that are 2.3% smaller in diameter ? I want to run 255 40 18 on my aftermarket wheels.

oo7spy

Not critical at all as long as they have a proper load rating.

BDoggPrelude

255/45/18 is better, if you ask me.

M T L T L

They are closer to the stock diameter with 1.46% difference but they are on the bigger side. It will add to the sidewall height. I prefer the thinner look if it wont put too much stress on the drivetrain.

Mr. Bond, does a lower profile tire inherently offer lower load rating even with wider patch compared to beefier sidewall tires ?

oo7spy

Mr. Prelude is actually the tire expert and the best to answer that question. Perhaps the better question is, "Mr. Prelude, what is it about the 45 profile that makes it better in your opinion? Is it simply the options available?"

BDoggPrelude

Personally, I never recommend going to a smaller overall diameter tire. If you notice plus sizing through most mainstream tire sizes, for example: moving from a 245/50R17 to 245/45R18, the load ranges all stay relatively close to each other. Once you start drastically changing overall tire diameters you start running into more issues with load ratings. No, you're not drastically changing sizes but you are basically going down one full size in tire. Sure, you're going to get that lower profile sidewall look but you're also going to increase fender to tire gap which, if you ask me, looks a whole lot worse than having a bigger sidewall.

Everything in the 255/45R18 will be more than enough load capacity for the RL as that size was originally designed for the Audi A8 and VW Phaeton so that is not a concern. About half of the tires made in a 255/40R18 are equal or higher than the OE tire load rating and half fall slightly short of it. I would still highly recommend just sticking with a 245/45R18. You get the most options, probably the best pricing in general and you're not changing anything in regards to the speedometer. There really is not that big of a difference in width between a 245 and a 255. You're talking about 1 centimeter. There could be that much difference in tread width just when comparing different brands of tires within the same size.

If you want a shorter sidewall you should do it the right way by increasing your wheel size. 17" wheel gets a 50-aspect ratio, 18"=45, 19"=40, 20"=35, etc.

Edit: Also, in case it matters to you, you will be racking up about 2.5% more miles on your odometer.

M T L T L

What is the minimum or the recommended Tire load index for the RL. I read somewhere the stockies came with 98V.

BDoggPrelude

98 for the 245/50R17 and 96 for the 245/45R18. I wouldn't recommend going any lower than 96.

M T L T L

I've found a set of used Yokohama tires in 255 40 18, very good price, Im tempted but they are 95W rated.

BDoggPrelude

I'm going to be as nice about this as I possibly can because I deal with this kind of thing on a daily basis and I'm on vacation from work this week...

The difference between a 95 and 96 load rating is 44lbs of capacity. Do I think you'll have any safety issues by dropping to a 95 load rating? Probably not. Do I think driving around on 95 load rated tires with an acceptable level of tread depth is probably safer than bald 96 load rated tires? Yes. Do I think that somebody that owns a flagship luxury vehicle should be able to afford quality new tires for their car? Yes.

M T L T L

My decision was made after ur earlier post. I only stated about the deal on this tire to reveal the reason behind my initial question. There's no way im going to buy these.

M T L T L

I landed a good set of tires michelin pilot sport. They are 265 40 18. They will go on my 8 inch wide +40 or 42 offset. Car is on Aspec suspension, any chance of rubbing them fenders with car loaded with people ?

BDoggPrelude

I doubt it. Hard to say without actually trying it though. I have 255/35R20's on a 9" wide wheel with a +35 offset. They rub a tiny bit in the rear over big dips but my tires have a 1/3" taller sidewall and my wheels stick out 20mm more than yours. I'm also on stock suspension.

M T L T L

It probably wont rub but Im getting concerned about fitting 265 on 8inch rims. It will fit but how fit n snug will it stay on the rims and not pop out.

BDoggPrelude

Good call. 265/40/18 has a 9-10.5" recommended rim width range. You're pretty far off at 8".

M T L T L

So I went to the shop yesterday. I saw the tires, the were beautiful, around 80% thread life on them. After mounting all the tires on the car that I notice 2 of the tires are 255 40 18 n the other two are 265 40 18. It really fucked up my day. I took them off n put back my winter on oem wheels. I did a quick calculation between the 2, theres 1.2% difference if I wanted to put the 255s in front n 265 in the rear but I said naa. The only scary thing is that I noticed this difference once I got home. I called the shop n went back. So I drove about 20 miles round trip with 2 different tire size on each side of the car.

oo7spy

Are there no tire shops in Canada that stock 4 brand new tires and know what they are doing?

M T L T L

Diapers n baby formula sit on top of my budget and I don't like cheap chinese tires so im left with slightly used high end tires. Here in my province, the law requires dedicated winter tires from December to March. That already multiply the cost by 2 compared to you guys. What happened in this case is they were thinking the set they sold me was 265 without really reading all 4 of them b4 I saw it myself.

BDoggPrelude

You seem to think people in Canada are the only people that run dedicated winter tires. I have 17" winter and 20" summer tires for my car along with 17" snow and 18" summer tires for my wife's car. It's also not necessarily two times the cost. It's double the buy-in cost initially but after that it's really not that much more expensive due to the fact that your tires last roughly twice as long.

On DiscountTireDirect.com you can get a set of four 245/45R18 Kumho Ecsta 4X tires delivered to your door in Canada for $583 as well as a $60 rebate on the tires. If you go with their financing you can get 6 months interest free plus an additional $30 rebate. That's $493 for 4 mid-grade, safe, brand new tires in the proper size for your car and 6 months to pay them off. Is that doable for you?

M T L T L

I guess I have to do better shopping around. I had put 550$ on the tires in question b4 taking them off. I have no experience buying tires from online retailers. But in shops, tires are around 30% more expensive than south the border. All the places I looked for some good new tires came around 1200$ for the set.

BDoggPrelude

I have a friend that moved to Canada from Colorado. He and his wife have 3 cars and each time they drive down to visit he brings a different car to me for new tires so I know tires are more expensive up there...but the internet is a wonderful thing. I am usually not an advocate of buying tires online just because they are something that needs constant servicing, often require warranty work and most local retailers will match online pricing anyway. There must be some big chain tire store up there that has a low price guarantee that will price match DiscountTireDirect's price. If not, fuck them, order online. DiscountTireDirect has exceptional service. It might be a good idea to invest the extra ~$20/tire for the certificates for free replacement in case you have an issue.

M T L T L

I might go that way. Theres also a Canadian online retailer 1010tires.com.

oo7spy

Me too. It wasn't until I read that they put two different size on each side of the car that I was concerned. I second BDogg about Discount Direct. I am all about doing a little extra for a good deal, but after reading the past 3 threads about used tires, there are definitely some things that can be worth paying a little extra to avoid hassle.