Senior Editor Mike Allen answers readers' car questions.

Q: Always enjoy your column. Was just reading the September issue and noticed the article on "Caught Flat-Not". My wife cannot do the spare either and in the past I had the slime and plug-in compressor for her also. Recently purchased a Kia Sedona and I discovered and interesting tidbit regarding this. (Yes I am one of those who reads the entire manual on a new car!) Anyway the TPMS (tire pressure monitoring system) makes the following statement: "Notice: Do not use any tire sealant if your vehicle is equipped with a TPMS, as the liquid sealant can damage the tire pressure sensors." In an emergency I would rather pay for a new sensor rather than have my wife stuck by the side of the road, but its an expense to consider. In the meantime, we will rely on the cell phone/AAA membership whenever possible. GARY KNOWLTON

A: Point well taken. Some TPMS uses a separate sensor, while others simply interpolate data about tire rotation from the ABS. The first type will not tolerate use of tire sealants.

Q: I have a 1995 Ford Explorer and the radio just didn’t work one day. All the stations appear on the screen but no volume is heard over the speakers. The antenna usually goes up when the radio is turned on and I thought that might be the problem. I pulled the antenna up and tried the radio again with still no sound. Can you please tell me what is wrong with my car? SETH WEAVER

A: If the problem was with the antenna, you'd hear a hiss from the speakers like there was no station on that channel. And you say there is no noise from any of the speakers, even though the screen shows the stations. Ipso facto, there is power to the radio. Tha only leaves the radio itself. It will need to be removed and repaired or replaced.

Q: I am ready to replace my OEM tires on my 1998 Ford F-150 4x2 supercab. I only drive about 5000 miles a year, do not haul anything heavy, mostly for recreational use. Seldom drive the interstate and only at moderate speeds. The original tires on the vehicle are P235/70rx16sl bsw a/s. I have an opportunity to replace them with the following: P245/75/16 Michilen tires. Can I do so safely? RUDOLPH ZURI

A: Yes you can.

Q: I have been crawling the net in an attempt to discover the nature of the torque produced by an XB12S Buell Lightning. Everybody repeats what is in the company catalogue (85 lbft @ 6000 rpm) and many say that torque is available from idle speed. One might argue that a peak torque produced so close to max bhp is pretty poor. What has happened to the simple practice of printing a torque curve? It is easy then to draw your own conclusion if you see that 90% of peak toque is produced at 1800rpm. Can you get your hands on the info? DEREK OLDHAM

A: The Motor Company does not provide this data to journalists. However, I've ridden the XB12S, and it's very torquey right down to idle. I just wished it revved higher.

Q: A couple months ago, I believe you had a column on replacing the pins in an electrical connector. Where can you find the tools and replacement parts? I have checked with dealers and parts stores and get nothing but blank stares. Internet searches have also turned up nothing. I can usually muddle through with improvised tools and salvage the connector pins, but it takes a lot of time. TERRY KIMBALL

A: I just went into the local NAPA store and asked the counterman. He had at least three different tools and kits to choose from. The one in the article is from Standard Motor Products, the whole kit was less than $100. There are cheaper ones, though.

Q: Is it true that you can add ethanol to your petrol, and will it increase the number of kilometres you get per litre? If you can, what volume would be optimal? C.G. COETZEE

A: Adding ethanol to gasoline will reduce the economy, i.e., you will get fewer miles per gallon, not more. Adding more than 10% ethanol to a vehicle not flex-fuel-rated can damage the fuel injection system.

Q: We are looking for an online assembly manual for a Nissan 1400 engine, as we have one that is stripped and this is a first time beginners. Do you perhaps know where we can find one? We are in New Zealand.

A: Popular Mechanics is published in the USA. I have no access to any service information for vehicles that were not on sale in the USA.

Q: I own a 1995 Oldsmobile Cutlass Ciera SL with a 3.1 liter V-6 engine. I am in the market for new tires and I wanted to purchase a safer and better performing tire this time. I currently have Cooper tires and they are OK, but I am not impressed with the overall performance of them. They seem to wear out too quickly, are too noisy on the highway, and are marginal in rain and snow. This is the second set of Cooper tires that I have owned. My initial reason for purchasing the Cooper tires was primarily cost and secondary, the reputation of the manufacturer and their product.

Unfortunately the 14 inch tires are becoming a thing of the past, or so I have been told by many local distributors that I spoke to today. In fact none of the local tire dealers I had contacted had any 14 inch tires in stock. They also explained that they can no longer obtain this tire size through any of the name brand manufacturers with the exception of GoodYear and even then it would have to be special ordered.

Can I safely put 15 inch rims on my car so that I am able to purchase a readily available name brand tire size from a local tire distributor?". Or do you have any information on an alternative brand tire that is readily available in 14 inch sizes, that is also equal in safety and performance ratings to the big name brands?

A: I'd get four recycled 15" rims and not only improve the range of tires available, but improve the ride and traction at the same time.

Q: In order to have a more tightly sealed gas tank and to avoid having the gas evaporate every time i fill up, I wrap a piece of plastic (cut out of a market plastic bag) on the gas tank cap. Does this do any damage to my car in general? ALEXANDER RUFO

A: Your fuel tank is already sealed as much as practical to prevent hydrocarbons from evaporating and causing air polution. The extra plastic won't help, and I fear that an errant piece of plastic might get into the tank and clog your fuel pump.

Q: How do I find a diagram for a 1998 ford ZX2 serpentine belt?

A: If the sticker under the hood is illegible and someone's stolen the manual, go to alldatadiy.com. B. DREXLER

Q: I have a 2003 Ford Windstar with 85000 miles. When traveling down the highway the car shudders, but only for a few seconds at a time. The shuddering acts up every so often, say approx. every 10 minutes or so? It feels like it could be a tire, but I have had them checked out. I had the plugs and wires changed, use high octane gas, changed the fuel and air filters. The car still shudders, any suggestions? J.C. O'CONNOR

A: Temporarily disconnect the torque converter clutch wiring harness to see if it affects the shudder. If this cures it, reconnect it and stop worrying.

Q: Do you have any data on the Vortex Valve? Has it been tested?

A: It's not a valve, and it doesn't create a vortex. It doesn't work. I tested one last month on a chassis dynomometer.